Laser In-Situ Keratomileusis (LASIK)

Definition
Purpose
Demographics
Description
Diagnosis/Preparation
Aftercare
Risks
Normal results
Morbidity and mortality rates
Alternatives

Definition

Laser in-situ keratomileusis (LASIK) is a non-reversible refractive procedure performed by ophthalmologists to correct myopia, hyperopia, or astigmatism. The surgeon uses an excimer laser to cut or reshape the cornea so that light will focus properly on the retina.

Purpose

LASIK is an elective surgery for patients who want to permanently correct myopia (nearsightedness), hyperopia (farsightedness), or astigmatism without eyeglasses, contact lenses, or refractive surgical procedures. The goal for most patients is to be free of any type of corrective lenses. Some patients may find wearing eyeglasses or contact lenses interferes with their careers or hobbies. Many professional athletes have chosen LASIK to improve their performance. However, patients with higher degrees of refractive error will still need some type of corrective lens.

LASIK is most commonly performed on myopes. For myopia, the surgeon flattens the cornea; for hyperopia, the surgeon steepens the cornea. Surgeons correct astigmatism by creating a normally shaped cornea with the excimer laser.

A new type of LASIK also can treat contrast sensitivity as well as refractive error. Custom LASIK incorporates new eye mapping technology into standard LASIK. The surgeon measures the eye from front to back creating a three dimensional corneal map. This much-more detailed map gives surgeons more specific information for the excimer laser and enables them to correct other abnormalities besides refractive error.

Demographics

LASIK candidates have myopia, hyperopia, or astigmatism; are 18 or older; and have had stable vision for at least two years. The American Academy of Ophthalmology (AAO) estimated that 1.3 million refractive surgery procedures were performed in 2002. LASIK was estimated to account for 95% of those procedures.

The first LASIK patients in the late 1990s were in the upper class, or upper middle class, and in their early 30s to mid-40s. The market was limited for the elective procedure that at first could range as expensive as $5,000 per eye. The number of younger patients receiving LASIK (in their early to mid-20s) was expected to rise in 2003 and beyond. The number of procedures also was expected to increase as prices continued to stabilize, and surgery centers and physicians offered payment plans.

Description

LASIK is a relatively new procedure. In April 1985, German physician Theo Seiler was the first to use an excimer laser to attempt to correct astigmatism in blind eyes. Experiments with excimer lasers on blind eyes were also completed in the United States in the mid-1980s. The term LASIK was invented by Greek ophthalmologist Ioannis Pallikari, the first surgeon to

use the hinged flap technique. Dr. Stephen Brint, as part of a clinical trial in 1991, performed the first LASIK procedure in the United States.

As of 2003, there are two types of LASIK. The standard LASIK procedure and custom LASIK, which relatively few surgeons have the technology to perform.

KEY TERMS

Ablation— During LASIK, the vaporization of eye tissue.

Astigmatism— Asymmetric vision defects due to irregularities in the cornea.

Cornea— The clear, curved tissue layer in front of the eye. It lies in front of the colored part of the eye (iris) and the black hole in the center of the iris (pupil).

Corneal topography— Mapping the cornea’s surface with a specialized computer that illustrates corneal elevations.

Dry eye— Corneal dryness due to insufficient tear production.

Enhancement— A secondary refractive procedure performed in an attempt to achieve better visual acuity.

Excimer laser— An instrument that is used to vaporize tissue with a cold, coherent beam of light with a single wavelength in the ultraviolet range.

Hyperopia— The inability to see near objects as clearly as distant objects, and the need for accommodation to see objects clearly.

Intraocular lens (IOL) implant— A small, plastic device (IOL) that is usually implanted in the lens capsule of the eye to correct vision after the lens of the eye is removed. This is the implant used in cataract surgery.

Macular degeneration— A condition usually associated with age in which the area of the retina called the macula is impaired due to hardening of the arteries (arteriosclerosis). This condition interferes with vision.

Microkeratome— A precision surgical instrument that can slice an extremely thin layer of tissue from the surface of the cornea.

Myopia— A vision problem in which distant objects appear blurry. Myopia results when the cornea is too steep or the eye is too long and the light doesn’t focus properly on the retina. People who are myopic or nearsighted can usually see near objects clearly, but not far objects.

Nomogram— A surgeon’s adjustment of the excimer laser to fine-tune results.

Presbyopia— A condition affecting people over the age of 40 where the system of accommodation that allows focusing of near objects fails to work because of age-related hardening of the lens of the eye.

Retina— The sensory tissue in the back of the eye that is responsible for collecting visual images and sending them to the brain.

Stroma — The thickest part of the cornea between Bowman’s membrane and Decemet’s membrane.

Standard LASIK

Standard LASIK takes from 10 to 20 minutes to perform and the results are immediate. It’s standard practice in LASIK operating rooms to have a clock on the wall so patients immediately can note they are able to read a clock face or other items that previously were blurry.

Immediately before the procedure, the ophthalmologist may request corneal topography (a corneal map) to compare with previous maps to ensure the treatment plan is still correct. The surgeon may also measure the cornea’s thickness if he didn’t previously. After these tests, a technician or co-managing optometrist will perform a refraction to make sure the refractive correction the surgeon will program into the laser is correct.

Three sets of eye drops will be administered twice before surgery. The first drop anesthetizes the cornea, the second drop prevents infection and the third drop controls inflammation after LASIK. Patients may be given a sedative, such as Valium. This is administered to calm nervous patients or to help patients sleep after the procedure.

After the prep work is completed, the patient reclines on a laser bed and the surgeon is seated directly behind the patient. If the procedure is being done on both eyes on the same day, the surgeon will patch the second eye. An eyelid speculum is inserted in the eye to be treated first to hold the eyelids apart. The patient stares at the blinking light of a laser microscope and must fixate his or her gaze on that light. The patient must remain still throughout the procedure.

The surgeon checks the refractive numbers on the laser. Because each patient’s cornea is shaped differently, the surgeon may have to adjust the level of correction. Laser companies provide an algorithm to determine the correction level, and the surgeon may alter the level because of a patient’s special needs. The adjustments are called nomograms. After the adjustments, the surgeon checks the microkeratome blade for defects.

The surgeon then indents the cornea to mark the flap location. The surgeon places a suction ring in the center of the sclera. A technician will activate the microkeratome’s suction. The patient’s vision dims at this point. The surgeon tests pressure by touching the cornea with a tonometer. Before using the microkeratome, sterile saline solution is squirted into the suction ring to lubricate the cornea. The microkeratome head is placed in the gear tracks of the suction ring, and the surgeon guides the microkeratome across the suction ring to create a flap. The microkeratome stops just short of traveling completely across the cornea. It leaves a hinge of tissue, commonly called a flap. After the flap is created, the surgeon removes the suction ring and slips a spatula under it and moves it to the side, exposing the stroma(inner cornea).

Once the stroma is exposed, the laser ablation begins, ranging from 30 to 60 seconds. The ablation flattens the cornea of myopic patients; steepens the cornea of hyperopic patients; and reshapes the cornea of astigmatic patients. After the ablation, the surgeon replaces the flap. More saline solution is squirted to remove any debris and enable the flap to move back into place without interruption. The surgeon ensures the flap is in place and removes any wrinkles. The surgeon places a shield over the eye to keep the flap in place. No stitches are used.

If bilateral LASIK is being performed, the patient must remain still while he is prepared for treatment on the remaining eye.

Custom LASIK

About half of all LASIK procedures are deemed “custom” LASIK. The difference between standard LASIK and custom LASIK lies in the diagnosis and who can be treated. With custom LASIK, surgeons use a wavefront analyzer (aberrometer) that beams light through the eye and finds irregularities based on how the light travels through the eye. It creates a three-dimensional corneal map to create a customized pattern for each patient. For standard LASIK, each patient with the same refractive error is treated with the same setting on the excimer laser, barring a few adjustments. The new technology individualizes treatment not only for refractive errors, but also for visual disorders that previous corneal mapping technology could not detect. As of early 2003, there was only one FDA-approved laser capable of the customized ablations, but others were awaiting approval.

Besides the customized excimer laser, the surgical procedure is the same. Surgeons now can treat patients who have higher-order aberrations, such as contrast sensitivity. Therefore, custom LASIK can successfully treat glare, night vision and other contrast problems.

Diagnosis/Preparation

Before LASIK, patients need to have a complete eye evaluation and comprehensive medical history taken. Soft contact lens wearers should stop wearing their lenses at least one week before the initial exam. Gas permeable lens wearers should not wear their lenses from three weeks to a month before the exam. Contact lens wear can alter the cornea’s shape, which should be allowed to return to its natural shape before the initial exam.

The initial exam

During the first exam, the surgeon’s staff will take a comprehensive medical history to determine if there are underlying medical problems that will prevent a successful surgery. This screening process will determine patients who should not have the procedure including:

• pregnant women or women who are breastfeeding
• patients with very small or very large refractive errors
• patients with low contrast sensitivity
• patients with scarred corneas or macular disease
• people with autoimmune diseases
• diabetics
• glaucoma patients
• patients with persistent blepharitis

The physician will also ask about medication. Some prescription medicines have been known to cause post-surgical scarring or cause flecks under the corneal flap. It is important for the patient to disclose any prescriptions or over-the-counter medicines taken regularly. Allergies to prescription medicine must also be discussed.

A complete eye exam will be performed to determine refractive error, uncorrected visual acuity and best corrected visual acuity. A cycloplegic refraction using eye drops to dilate the pupils also will be performed. Other examination procedures include corneal mapping, a keratometer reading to determine the curvature of the central part of the cornea, a slit lamp exam to determine any damage to the cornea and evidence of glaucoma and cataracts. A fundus exam also will be performed to check for retinal holes and macular degeneration and macular disease. Other tests are done to rule out glaucoma.

While those tests check general eye health, others more closely relate to the outcome of LASIK surgery. A corneal pachymeter measures the cornea’s thickness. This is important because surgeons remove tissue during surgery. A pupilometer measures the pupil when it is naturally dilated in a dark room without drops. Patients with large pupils have been known to have complications after LASIK, such as glare and halos.

Treatment options/Informed consent

After the exam, the patient and physician discuss treatment options and expectations. Patients who expect to see perfectly after LASIK are usually not considered good candidates because they usually are dissatisfied with the results. Surgeons also discuss how patients will handle presbyopia, which occurs during the patient’s 40s. LASIK does not correct for presbyopia, and patients will need reading glasses to accommodate for reading when presbyopia occurs. Sometimes patients 40 and older opt for monovision to treat presbyopia, where one eye is left untreated or one eye is only partially corrected. Monovision means one eye is for short-term vision and the other is for distance vision.

The doctor will advise the patient of any possible LASIK complications, explain the procedure and answer questions. After deciding on a treatment option, the patient is required to sign an informed consent form.

At this time, payment will also be discussed. Insurance usually does not cover LASIK, although some offer a limited benefit for the procedure. Some laser centers offer payment plans and some physicians have begun using credit companies to handle payments. LASIK can cost anywhere from $999 to $3,000 per eye. The cost varies greatly from surgeon to surgeon. Most of the fees are global, and cover all the pre-operative and postoperative exams as well as the procedure. Patients should be advised of what the fee covers, and if retreatments to the original surgery are included in that price.

Presurgery preparations

The patient is advised to discontinue contact lens wear immediately and refrain from using creams, lotions, make-up or perfume for at least two days before surgery. Patients may also be asked to scrub their eyelashes for a period of time to remove any debris. Patients also must find transportation to and from the surgery, and also to and from the first postoperative visit. Medication and distorted vision make it unsafe for the patients to drive after LASIK.

Aftercare

After LASIK, patients may experience burning, itching or a foreign body sensation. They should be advised not to touch the eye as that could damage the flap. Many physicians recommend sleeping after the surgery. Patients may also experience glare, starbursts, or halos that should improve after the first few days. Patients are advised to seek help immediately if they feel severe eye pain, or if symptoms worsen.

The first follow-up visit is 24-48 hours after surgery. The physician will remove the eye shield, check the patient’s vision, and may prescribe more antibiotic drops or artificial tears. Patients must refrain from strenuous activity, such as contact sports, for at least a month. The use of creams, lotions, and make-up must also be avoided for at least two weeks. Hot tubs and swimming pools should be avoided for at least two months. Patients are advised that refraining from these activities and products will help stem infection and aid healing of the cornea.

Patients will have regularly scheduled visits post-LASIK for at least six months. Vision gradually improves the first few months after surgery. In some cases, if the vision does not meet expectations and the surgeon believes it can be further corrected, he will perform an enhancement. Enhancements are usually done for undercorrection. Overcorrected patients usually need eyeglasses or contact lenses.

Risks

Surgeons separate LASIK complications into two categories.

Intraoperative risks

• Cornea perforation. This complication has almost disappeared because of advances in microkeratome design.
• Flap complications. Newer microkeratomes also have reduced the likelihood of “free caps,” where the cap becomes unhinged. An experienced surgeon replaces the cap after ablation. In some cases, the procedure must be aborted while the eye heals.
• Laser hot spots. Higher energy surrounding the laser beam can cause irregular astigmatism. Proper laser testing before the procedure eliminates this risk.
• Central islands. This refers to a raised area in the central part of the treated zone that receives insufficient laser treatment. Any raised area can decrease the laser’s effectiveness. The island either shrinks by itself or can be remedied with retreatment.
• Decentered ablation. This occurs when the laser beam is aimed incorrectly. This can result in permanent halos and ghost images.

Postoperative complications

• Undercorrection or overcorrection. Undercorrection can usually be treated with an enhancement, but overcorrection will require the use of eyeglasses or contact lenses.
• Debilitating symptoms. These can be permanent or transient, and include glare, halos, double vision and poor nighttime vision. Some patients may also lose contrast sensitivity.
• Dry eye. This also can be permanent or transient. Most patients experience some dry eye immediately after surgery. Some patients continue to experience dry eye and are treated with artificial tears or punctal plugs.
• Displaced flap. Occurs after the eye is hit or rubbed. If immediate attention is given by the surgeon, who must lift the flap and clean under it, no long-term effects occur.
• Nonspecific diffuse intralamellar keratitis. Commonly known as Sands of the Sahara, this complication can range from corneal haze to eye clouding that resembles swirling sand. It is treated with topical steroids, although severe cases may require eye irrigation.
• Epithelial ingrowth. The cells of the lower cornea migrate under the corneal cap. The surgeon must lift the cap and remove the cells. If untreated, vision is impaired.
• Striae. These are wrinkles in the flap that can reduce visual acuity. The surgeon must lift the corneal flap and smooth the wrinkles.
• Photophobia. Extreme sensitivity to light can last a few days or a week after surgery.
• Infection. This rarely occurs after LASIK. It is treated with antibiotics.

Normal results

After LASIK, most patients are able to see well enough to pass a driver’s license exam without glasses or contact lenses. Some patients will still need corrective lenses, but the lenses won’t need to be as powerful.

Because LASIK is a relatively new procedure, there is limited information on long-term regression. If patients are being treated for myopia, they should be aware they will have to rely on spectacles with the onset of presbyopia.

Morbidity and mortality rates

Information about mortality rates following LASIK is limited because the procedure is elective. Complications that can lead to more serious conditions, such as infection, are treated with topical antibiotics after LASIK. The most serious possible complication from LASIK is blindness from an untreated complication. As of 2000, there had been no reports of blindness-induced LASIK. One incidence of legal blindness was reported after a severely myopic patient had retinal hemorrhages. However, it was inconclusive whether or not LASIK was the causative agent.

Alternatives

Nonsurgical alternatives

Nonsurgical alternatives to LASIK are contact lenses and eyeglasses, which can also correct refractive errors. Continuous-wear contact lenses, which a patient can sleep in for as long as 30 days, can provide the same effect as LASIK if the patient wants good vision upon waking. Orthokeratology involves a rigid gas permeable contact lens the patient wears for a predetermined amount of time to reshape the cornea. After removing the lens, it takes weeks for the cornea to return to its normal shape. At that time, the patient repeats the process.

Corneal rings and implants are another alternative for myopes. These require surgery without lasers and involve a corrective lens surgically implanted in the eye. One of the biggest benefits to these procedures is that they are reversible. However, they may not provide the crisp vision of a successful LASIK. There also are several different types of intraocular lenses being tested to treat myopia and hyperopia.

Surgical alternatives

There also are surgical alternatives to LASIK. They include:

• Conductive keratoplasty. This uses radio frequency waves to shrink corneal collagen. It is used to treat mild to moderate hyperopia.
• Photorefractive keratectomy (PRK). PRK also uses an excimer laser and is similar to LASIK. However, in PRK, the surface of the cornea is removed by the laser. PRK patients have a longer recovery time and may need steroidal eye drops for months after surgery. Its success rate is similar to that of LASIK.
• Radial keratotomy (RK). RK was the first widely used surgical correction for mild to moderate myopia. The surgeon alters the shape of the cornea without a laser. This is one of the oldest refractive procedures, and has proved successful on lower and moderate corrections.
• Astigmatic keratotomy (AK). AK is a variation of RK used to treat mild to moderate astigmatism. AK has proved successful if the errors are mild to moderate.
• Laser thermal keratoplasty (LTK). LTK was approved as to treat hyperopia in 2000. An LTK patient’s vision

WHO PERFORMS THE PROCEDURE AND WHERE IS IT PERFORMED?

An ophthalmologist performs LASIK, but because it is a relatively new technology, the surgeon may not have received training as part of his residency. It is more likely the surgeon has completed continuing medical education courses or may have had training provided by the laser companies. He may also have received training as part of membership in an organization such as the American Society of Refractive Surgeons.

Before and aftercare probably will be provided by a co-managing optometrist. The optometrist usually performs the pre- and postoperative exams, and also discusses the patient’s suitability for LASIK and any potential problems.

Ophthalmic technicians may perform preliminary testing, including corneal topography and corneal measuring. Laser technicians are required to have special training provided by the laser manufacturer.

Surgeons may perform LASIK in a hospital where they rely on the hospital staff for support. Because lasers are expensive, some surgeons pool their resources and purchase a laser that they share at a freestanding surgery center. LASIK is also provided by surgeons at surgery centers owned by refractive surgery companies. These businesses hire support staff, optometrists and surgeons to perform LASIK.

is overcorrected for one to three months, and the effect of improved near vision may diminish over time as distance vision improves. Some regression has been noted.

Resources

BOOKS

Yanoff, M et al. Ophthalmology. 2nd ed. St. Louis: Mosby, 2004.

ORGANIZATIONS

American Academy of Ophthalmology. PO Box 7424, San Francisco, CA 94120-7424 (415) 561-8500. http://www.aao.org

American Society of Cataract and Refractive Surgery. 4000 Legato Road, Suite 850, Fairfax, VA 22033-4055. (703) 591-2220. <ascrs@ascrs.org>. http://www.ascrs.org.

QUESTIONS TO ASK THE DOCTOR

• How many LASIK procedures have you performed and how long have you been performing them?
• Who will handle the aftercare, the ophthalmologist or co-managing optometrist?
• What is the experience of the laser support team?
• How many of your patients achieve 20/20 or better?
• What percentage of your patients have serious complications? Minor complications?
• Who will treat complications, if any, after the procedure?
• If the patient needs an enhancement, is that an extra expense, or is it covered in the original fee?

OTHER

“Basik Lasik: Tips on LASIK Eye Surgery.” Federal Trade Commission. August 2000 [cited February 22, 2003]. http://www.ftc.gov/bcp/conline/pubs/health/lasik.htm.

Croes, Keith. “Custom LASIK: The Next Generation in Laser Eye Surgery.” All About Vision. [cited February 22, 2003]. http://www.allaboutvision.com/visionsurgery/custom_lasik.htm.

Gonzalez, Jeanne Michelle. “To Increase LASIK Volume, Know Your Market.” Ocular Surgery News. September 1, 2002 [cited February 23, 2003]. http://www.osnsupersite.com/view.asp?ID=3473.

Gottlieb, Howard O.D. “The Changing LASIK Patient.” Ophthalmology Management. February 2001 [cited February 22, 2003]. http://www.ophmanagement.com/archive_results.asp?loc=archive/2001/february/0201038.htm.

“LASIK Eye Surgery.” U.S. Food and Drug Administration Center for Devices and Radiological Health. October 1, 2002 [cited February 20, 2003]. http://www.fda.gov/cdrh/lasik.

“Refractive Errors and Refractive Surgery.” American Academy of Ophthalmology. [cited February 23, 2003]. http://www.aao.org/aao/newsroom/facts/errors.cfm.

Mary Bekker

Laser in-situ keratomileusis (LASIK)

Definition

Laser in-situ keratomileusis (LASIK) is a non-reversible refractive procedure performed by ophthalmologists to correct myopia, hyperopia, or astigmatism. The surgeon uses an excimer laser to cut or reshape the cornea so that light will focus properly on the retina.

Purpose

LASIK is an elective surgery for patients who want to permanently correct myopia (nearsightedness), hyperopia (farsightedness), or astigmatism without eyeglasses, contact lenses, or refractive surgical procedures. The goal for most patients is to be free of any type of corrective lenses. Some patients may find wearing eyeglasses or contact lenses interferes with their careers or hobbies. Many professional athletes have chosen LASIK to improve their performance. However, patients with higher degrees of refractive error will still need some type of corrective lens.

LASIK is most commonly performed on myopes. For myopia, the surgeon flattens the cornea; for hyperopia, the surgeon steepens the cornea. Surgeons correct astigmatism by creating a normally shaped cornea with the excimer laser.

A new type of LASIK also can treat contrast sensitivity as well as refractive error. Custom LASIK incorporates new eye mapping technology into standard LASIK. The surgeon measures the eye from front to back creating a three dimensional corneal map. This much-more detailed map gives surgeons more specific information for the excimer laser and enables them to correct other abnormalities besides refractive error.

Demographics

LASIK candidates have myopia, hyperopia, or astigmatism; are 18 or older; and have had stable vision for at least two years. The American Academy of Ophthalmology (AAO) estimated that 1.8 million refractive surgery procedures were performed in 2002. LASIK was estimated to account for 95% of those procedures.

The first LASIK patients in the late 1990s were in the upper class, or upper middle class, and in their early 30s to mid-40s. The market was limited for the elective procedure that at first could range as expensive as $5,000 per eye. The number of younger patients receiving LASIK (in their early to mid-20s) was expected to rise in 2003 and beyond. The number of procedures also was expected to increase as prices continued to stabilize, and surgery centers and physicians offered payment plans.

Description

LASIK is a relatively new procedure. In April 1985, German physician Theo Seiler was the first to use an excimer laser to attempt to correct astigmatism in blind eyes. Experiments with excimer lasers on blind eyes were also completed in the United States in the mid-1980s. The term LASIK was invented by Greek ophthalmologist Ioannis Pallikari, the first surgeon to use the hinged flap technique. Dr. Stephen Brint, as part of a clinical trial in 1991, performed the first LASIK procedure in the United States.

As of 2003, there are two types of LASIK. The standard LASIK procedure and custom LASIK, which relatively few surgeons have the technology to perform.

Standard LASIK

Standard LASIK takes from 10 to 20 minutes to perform and the results are immediate. It's standard practice in LASIK operating rooms to have a clock on the wall so patients immediately can note they are able to read a clock face or other items that previously were blurry.

Immediately before the procedure, the ophthalmologist may request corneal topography (a corneal map) to compare with previous maps to ensure the treatment plan is still correct. The surgeon may also measure the cornea's thickness if he didn't previously. After these tests, a technician or co-managing optometrist will perform a refraction to make sure the refractive correction the surgeon will program into the laser is correct.

Three sets of eye drops will be administered twice before surgery. The first drop anesthetizes the cornea, the second drop prevents infection and the third drop controls inflammation after LASIK. Patients may be given a sedative, such as Valium. This is administered to calm nervous patients or to help patients sleep after the procedure.

After the prep work is completed, the patient reclines on a laser bed and the surgeon is seated directly behind the patient. If the procedure is being done on both eyes on the same day, the surgeon will patch the second eye. An eyelid speculum is inserted in the eye to be treated first to hold the eyelids apart. The patient stares at the blinking light of a laser microscope and must fixate his or her gaze on that light. The patient must remain still throughout the procedure.

The surgeon checks the refractive numbers on the laser. Because each patient's cornea is shaped differently, the surgeon may have to adjust the level of correction. Laser companies provide an algorithm to determine the correction level, and the surgeon may alter the level because of a patient's special needs. The adjustments are called nomograms. After the adjustments, the surgeon checks the microkeratome blade for defects.

The surgeon then indents the cornea to mark the flap location. The surgeon places a suction ring in the center of the sclera. A technician will activate the microkeratome's suction. The patient's vision dims at this point. The surgeon tests pressure by touching the cornea with a tonometer. Before using the microkeratome, sterile saline solution is squirted into the suction ring to lubricate the cornea. The microkeratome head is placed in the gear tracks of the suction ring, and the surgeon guides the microkeratome across the suction ring to create a flap. The microkeratome stops just short of traveling completely across the cornea. It leaves a hinge of tissue, commonly called a flap. After the flap is created, the surgeon removes the suction ring and slips a spatula under it and moves it to the side, exposing the stroma (inner cornea).

Once the stroma is exposed, the laser ablation begins, ranging from 30 to 60 seconds. The ablation flattens the cornea of myopic patients; steepens the cornea of hyperopic patients; and reshapes the cornea of astigmatic patients. After the ablation, the surgeon replaces the flap. More saline solution is squirted to remove any debris and enable the flap to move back into place without interruption. The surgeon ensures the flap is in place and removes any wrinkles. The surgeon places a shield over the eye to keep the flap in place. No stitches are used.

If bilateral LASIK is being performed, the patient must remain still while he is prepared for treatment on the remaining eye.

Custom LASIK

As of early 2003, a handful of ophthalmologists in the United States had the technology to perform custom LASIK. The difference between standard LASIK and custom LASIK lies in the diagnosis and who can be treated. With custom LASIK, surgeons use a wavefront analyzer (aberrometer) that beams light through the eye and finds irregularities based on how the light travels through the eye. It creates a three-dimensional corneal map to create a customized pattern for each patient. For standard LASIK, each patient with the same refractive error is treated with the same setting on the excimer laser, barring a few adjustments. The new technology individualizes treatment not only for refractive errors, but also for visual disorders that previous corneal mapping technology could not detect. As of early 2003, there was only one FDA-approved laser capable of the customized ablations, but others were awaiting approval.

Besides the customized excimer laser, the surgical procedure is the same. Surgeons now can treat patients who have higher-order aberrations, such as contrast sensitivity. Therefore, custom LASIK can successfully treat glare, night vision and other contrast problems.

Diagnosis/Preparation

Before LASIK, patients need to have a complete eye evaluation and comprehensive medical history taken. Soft contact lens wearers should stop wearing their lenses at least one week before the initial exam. Gas permeable lens wearers should not wear their lenses from three weeks to a month before the exam. Contact lens wear can alter the cornea's shape, which should be allowed to return to its natural shape before the initial exam.

The initial exam

During the first exam, the surgeon's staff will take a comprehensive medical history to determine if there are underlying medical problems that will prevent a successful surgery. This screening process will determine patients who should not have the procedure including:

• pregnant women or women who are breastfeeding
• patients with very small or very large refractive errors
• patients with low contrast sensitivity
• patients with scarred corneas or macular disease
• people with autoimmune diseases
• diabetics
• glaucoma patients
• patients with persistent blepharitis

The physician will also ask about medication. Some prescription medicines have been known to cause post-surgical scarring or cause flecks under the corneal flap. It's important for the patient to disclose any prescriptions or over-the-counter medicines taken regularly. Allergies to prescription medicine must also be discussed.

A complete eye exam will be performed to determine refractive error, uncorrected visual acuity and best corrected visual acuity. A cycloplegic refraction using eye drops to dilate the pupils also will be performed. Other examination procedures include corneal mapping, a keratometer reading to determine the curvature of the central part of the cornea, a slit lamp exam to determine any damage to the cornea and evidence of glaucoma and cataracts. A fundus exam also will be performed to check for retinal holes and macular degeneration and macular disease. Other tests are done to rule out glaucoma.

While those tests check general eye health, others more closely relate to the outcome of LASIK surgery. A corneal pachymeter measures the cornea's thickness. This is important because surgeons remove tissue during surgery. A pupilometer measures the pupil when it is naturally dilated in a dark room without drops. Patients with large pupils have been known to have complications after LASIK, such as glare and halos.

Treatment options/Informed consent

After the exam, the patient and physician discuss treatment options and expectations. Patients who expect to see perfectly after LASIK are usually not considered good candidates because they usually are dissatisfied with the results. Surgeons also discuss how patients will handle presbyopia, which occurs during the patient's 40s. LASIK does not correct for presbyopia, and patients will need reading glasses to accommodate for reading when presbyopia occurs. Sometimes patients 40 and older opt for monovision to treat presbyopia, where one eye is left untreated or one eye is only partially corrected. Monovision means one eye is for short-term vision and the other is for distance vision.

The doctor will advise the patient of any possible LASIK complications, explain the procedure and answer questions. After deciding on a treatment option, the patient is required to sign an informed consent form.

At this time, payment will also be discussed. Insurance usually does not cover LASIK, although some offer a limited benefit for the procedure. Some laser centers offer payment plans and some physicians have begun using credit companies to handle payments. LASIK can cost anywhere from $999 to $3,000 per eye. The cost varies greatly from surgeon to surgeon. Most of the fees are global, and cover all the pre-operative and post-operative exams as well as the procedure. Patients should be advised of what the fee covers, and if retreatments to the original surgery are included in that price.

Pre-surgery preparations

The patient is advised to discontinue contact lens wear immediately and refrain from using creams, lotions, make-up or perfume for at least two days before surgery. Patients may also be asked to scrub their eyelashes for a period of time to remove any debris. Patients also must find transportation to and from the surgery, and also to and from the first post-operative visit. Medication and distorted vision make it unsafe for the patients to drive after LASIK.

Aftercare

After LASIK, patients may experience burning, itching or a foreign body sensation. They should be advised not to touch the eye as that could damage the flap. Many physicians recommend sleeping after the surgery. Patients may also experience glare, starbursts, or halos that should improve after the first few days. Patients are advised to seek help immediately if they feel severe eye pain, or if symptoms worsen.

The first follow-up visit is from 24 to 48 hours after surgery. The physician will remove the eye shield, check the patient's vision, and may prescribe more antibiotic drops or artificial tears. Patients must refrain from strenuous activity, such as contact sports, for at least a month. The use of creams, lotions, and make-up must also be avoided for at least two weeks. Hot tubs and swimming pools should be avoided for at least two months. Patients are advised that refraining from these activities and products will help stem infection and aid healing of the cornea.

Patients will have regularly scheduled visits post-LASIK for at least six months. Vision gradually improves the first few months after surgery. In some cases, if the vision does not meet expectations and the surgeon believes it can be further corrected, he will perform an enhancement. Enhancements are usually done for under-correction. Overcorrected patients usually need eyeglasses or contact lenses.

Risks

Surgeons separate LASIK complications into two categories.

Intraoperative risks

• Cornea perforation. This complication has almost disappeared because of advances in microkeratome design.
• Flap complications. Newer microkeratomes also have reduced the likelihood of "free caps," where the cap becomes unhinged. An experienced surgeon replaces the cap after ablation. In some cases, the procedure must be aborted while the eye heals.
• Laser hot spots. Higher energy surrounding the laser beam can cause irregular astigmatism. Proper laser testing before the procedure eliminates this risk.
• Central islands. This refers to a raised area in the central part of the treated zone that receives insufficient laser treatment. Any raised area can decrease the laser's effectiveness. The island either shrinks by itself or can be remedied with retreatment.
• Decentered ablation. This occurs when the laser beam is aimed incorrectly. This can result in permanent halos and ghost images.

Post-operative complications

• Undercorrection or overcorrection. Undercorrection can usually be treated with an enhancement, but over-correction will require the use of eyeglasses or contact lenses.
• Debilitating symptoms. These can be permanent or transient, and include glare, halos, double vision and poor nighttime vision. Some patients may also lose contrast sensitivity.
• Dry eye. This also can be permanent or transient. Most patients experience some dry eye immediately after surgery. Some patients continue to experience dry eye and are treated with artificial tears or punctal plugs.
• Displaced flap. Occurs after the eye is hit or rubbed. If immediate attention is given by the surgeon, who must lift the flap and clean under it, no long-term effects occur.
• Nonspecific diffuse intralamellar keratitis. Commonly known as Sands of the Sahara, this complication can range from corneal haze to eye clouding that resembles swirling sand. It is treated with topical steroids, although severe cases may require eye irrigation.
• Epithelial ingrowth. The cells of the lower cornea migrate under the corneal cap. The surgeon must lift the cap and remove the cells. If untreated, vision is impaired.
• Striae. These are wrinkles in the flap that can reduce visual acuity. The surgeon must lift the corneal flap and smooth the wrinkles.
• Photophobia. Extreme sensitivity to light can last a few days or a week after surgery.
• Infection. This rarely occurs after LASIK. It is treated with antibiotics .

Normal results

After LASIK, most patients are able to see well enough to pass a driver's license exam without glasses or contact lenses. Some patients will still need corrective lenses, but the lenses won't need to be as powerful.

Because LASIK is a relatively new procedure, there is limited information on long-term regression. If patients are being treated for myopia, they should be aware they will have to rely on spectacles with the onset of presbyopia.

Morbidity and mortality rates

Information about mortality rates following LASIK is limited because the procedure is elective. Complications that can lead to more serious conditions, such as infection, are treated with topical antibiotics after LASIK. The most serious possible complication from LASIK is blindness from an untreated complication. As of 2000, there had been no reports of blindness-induced LASIK. One incidence of legal blindness was reported after a severely myopic patient had retinal hemorrhages. However, it was inconclusive whether or not LASIK was the causative agent.

Alternatives

Nonsurgical alternatives

Nonsurgical alternatives to LASIK are contact lenses and eyeglasses, which can also correct refractive errors. Continuous-wear contact lenses, which a patient can sleep in for as long as 30 days, can provide the same effect as LASIK if the patient wants good vision upon waking. Orthokeratology involves a rigid gas permeable contact lens the patient wears for a predetermined amount of time to reshape the cornea. After removing the lens, it takes weeks for the cornea to return to its normal shape. At that time, the patient repeats the process.

Corneal rings and implants are another alternative for myopes. These require surgery without lasers and involve a corrective lens surgically implanted in the eye. One of the biggest benefits to these procedures is that they are reversible. However, they may not provide the crisp vision of a successful LASIK. There also are several different types of intraocular lenses being tested to treat myopia and hyperopia.

Surgical alternatives

There also are surgical alternatives to LASIK. They include:

• Conductive keratoplasty. This uses radio frequency waves to shrink corneal collagen. It is used to treat mild to moderate hyperopia.
• Photorefractive keratectomy (PRK ). PRK also uses an excimer laser and is similar to LASIK. However, in PRK, the surface of the cornea is removed by the laser. PRK patients have a longer recovery time and may need steroidal eye drops for months after surgery. Its success rate is similar to that of LASIK.
• Radial keratotomy (RK). RK was the first widely used surgical correction for mild to moderate myopia. The surgeon alters the shape of the cornea without a laser. This is one of the oldest refractive procedures, and has proved successful on lower and moderate corrections.
• Astigmatic keratotomy (AK). AK is a variation of RK used to treat mild to moderate astigmatism. AK has proved successful if the errors are mild to moderate.
• Laser thermal keratoplasty (LTK). LTK was approved as to treat hyperopia in 2000. An LTK patient's vision is overcorrected for one to three months, and the effect of improved near vision may diminish over time as distance vision improves. Some regression has been noted.

Resources

books

Brint, Stephen F., M.D., Dennis Kennedy, O.D., and Corinne Kuypers-Denlinger. The Laser Vision Breakthrough Roseville, CA: Prima Health, 2000.

Caster, Andrew I., M.D., F.A.C.S. The Eye Laser Miracle: The Complete Guide to Better Vision New York, NY: Ballantine Books, 1997.

Slade, Stephen G., M.D., Richard Baker, O.D., and Dorothy Kay Brockman. The Complete Book of Laser Eye Surgery Naperville, ILL: Sourcebooks, Inc., 2000.

organizations

American Academy of Ophthalmology. PO Box 7424, San Francisco, CA 94120-7424 (415) 561-8500. <http://www.aao.org>

American Society of Cataract and Refractive Surgery. 4000 Legato Road, Suite 850, Fairfax, VA 22033-4055. (703) 591-2220. <ascrs@ascrs.org>. <http://www.ascrs.org>.

other

"Basik Lasik: Tips on LASIK Eye Surgery." Federal Trade Commission. August 2000 [cited February 22, 2003] <http://www.ftc.gov/bcp/conline/pubs/health/lasik.htm>.

Croes, Keith. "Custom LASIK: The Next Generation in Laser Eye Surgery." All About Vision [cited February 22, 2003]. <http://www.allaboutvision.com/visionsurgery/custom_lasik.htm>.

Gonzalez, Jeanne Michelle. "To Increase LASIK Volume, Know Your Market." Ocular Surgery News. September 1, 2002 [cited February 23, 2003]. <http://www.osnsupersite.com/view.asp?ID=3473>.

Gottlieb, Howard O.D. "The Changing LASIK Patient." Ophthalmology Management. February 2001 [cited February 22, 2003]. <http://www.ophmanagement.com/archive_results.asp?loc=archive/2001/february/0201038.htm>.

"LASIK Eye Surgery." U.S. Food and Drug Administration Center for Devices and Radiological Health. October 1, 2002 [cited February 20, 2003]. <http://www.fda.gov/cdrh/lasik>.

"Refractive Errors and Refractive Surgery." American Academy of Ophthalmology [cited February 23, 2003]. <http://www.aao.org/aao/newsroom/facts/errors.cfm>.

Mary Bekker

WHO PERFORMS THE PROCEDURE AND WHERE IS IT PERFORMED?

An ophthalmologist performs LASIK, but because it is a relatively new technology, the surgeon may not have received training as part of his residency. It is more likely the surgeon has completed continuing medical education courses or may have had training provided by the laser companies. He may also have received training as part of membership in an organization such as the American Society of Refractive Surgeons.

Before and aftercare probably will be provided by a co-managing optometrist. The optometrist usually performs the pre- and post-operative exams, and also discusses the patient's suitability for LASIK and any potential problems.

Ophthalmic technicians may perform preliminary testing, including corneal topography and corneal measuring. Laser technicians are required to have special training provided by the laser manufacturer.

Surgeons may perform LASIK in a hospital where they rely on the hospital staff for support. Because lasers are expensive, some surgeons pool their resources and purchase a laser that they share at a freestanding surgery center. LASIK is also provided by surgeons at surgery centers owned by refractive surgery companies. These businesses hire support staff, optometrists and surgeons to perform LASIK.

QUESTIONS TO ASK THE DOCTOR

• How many LASIK procedures have you performed and how long have you been performing them?
• Who will handle the aftercare, the ophthalmologist or co-managing optometrist?
• What is the experience of the laser support team?
• How many of your patients achieve 20/20 or better?
• What percentage of your patients have serious complications? Minor complications?
• Who will treat complications, if any, after the procedure?
• If the patient needs an enhancement, is that an extra expense, or is it covered in the original fee?

Laser Surgery

Precautions

Description

Types of lasers

Laser applications

Advantages of laser surgery

Disadvantages of laser surgery

Preparation

Aftercare

Risks

Normal results

Abnormal results

Resources

Laser (light amplification by stimulated emission of radiation) surgery uses an intensely hot, precisely focused beam of light to remove or vaporize tissue and control bleeding in a wide variety of non-invasive and minimally invasive procedures. Laser surgery is used to cut or destroy tissue that is abnormal or diseased without harming healthy, normal tissue; shrink or destroy tumors and lesions, and cauterize (seal) blood vessels to prevent excessive bleeding.

Precautions

Anyone who is thinking about having laser surgery should ask his doctor to explain why laser surgery is likely to be more beneficial than traditional surgery and to describe the experience in performing the laser procedure the patient is considering.

Because some lasers can temporarily or permanently discolor the skin, a dark-skinned patient should make sure that his surgeon has successfully performed laser procedures on people of color.

Some types of laser surgery should not be performed on pregnant women or on patients with severe cardiopulmonary disease or other serious health problems.

Description

The first working laser was introduced in 1960. The device was initially used to treat diseases and disorders of the eye, whose transparent tissues gave ophthalmic surgeons a clear view of how the narrow, concentrated beam was being directed. Dermatologic surgeons also helped pioneer laser surgery, and developed and improved upon many early techniques and more refined surgical procedures.

Types of lasers

There are three types of lasers most often used in medical treatment. The color of the light beam (within the laser) is directly related to the type of surgery performed (specifically, the color of the tissue involved). The carbon dioxide (CO₂) laser is primarily a surgical tool. This device converts light energy to heat, which is strong enough to minimize bleeding while it cuts through or vaporizes tissue). The neodymium:yttrium-aluminum-garnet (Nd:YAG) laser is capable of penetrating tissue more deeply than other lasers. The Nd:YAG makes blood clot quickly and can enable surgeons to see and work on parts of the body that could otherwise be reached only through open (invasive) surgery). The argon laser provides the limited penetration needed for eye surgery and superficial skin disorders. In a special procedure known as photodynamic therapy (PDT), this laser uses light-sensitive dyes to shrink or dissolve tumors.

Laser applications

Sometimes lasers are described as scalpels of light. Today, lasers are used alone or with conventional surgical instruments in a diverse array of procedures that, improve appearance, relieve pain, restore function, and save lives.

Laser surgery is often standard operating procedure for specialists in cardiology, dentistry, dermatology, gastroenterology (treatment of disorders of the stomach and intestines), gynecology, neurosurgery, oncology (cancer treatment), ophthalmology (treatment of disorders of the eye), orthopedics (treatment of disorders of bones, joints, muscles, ligaments, and tendons, otolaryngology (treatment of disorders of the ears, nose, and throat), pulmonary care (treatment of disorders of the respiratory system), and urology (treatment of disorders of the urinary tract and of the male reproductive system).

Routine uses of lasers include erasing birthmarks, skin discoloration, and skin changes due to aging, and removing benign, precancerous, or cancerous tissues or tumors. Lasers are used to stop snoring, remove tonsils, remove or transplant hair, and relieve pain and restore function in patients who are too weak to undergo major surgery.

Lasers are also used to treat angina (chest pain); cancerous or non-cancerous tumors that cannot be removed or destroyed; cold and canker sores, gum disease, and tooth sensitivity or decay; ectopic pregnancy (development of a fertilized egg outside the uterus); endometriosis; fibroid tumors; gallstones; glaucoma, mild-to-moderate nearsightedness, astigmatism and other conditions that impair sight; migraine headaches; non-cancerous enlargement of the prostate gland; nosebleeds; ovarian cysts; ulcers; varicose veins; warts; and numerous other conditions, diseases, and disorders.

Advantages of laser surgery

Often referred to as bloodless surgery, laser procedures usually involve less bleeding than conventional surgery. The heat generated by the laser keeps the surgical site free of germs and reduces the risk of infection. Because a smaller incision is required, laser procedures often take less time (and cost less money) than traditional surgery. Sealing off blood vessels and nerves reduces bleeding, swelling, scarring, pain, and the length of the recovery period.

Disadvantages of laser surgery

Although many laser surgeries can be performed in a doctor’s office rather than in a hospital, the person guiding the laser must be at least as thoroughly trained and highly skilled as someone performing the same procedure in a hospital setting. Imprecisely aimed lasers can burn or destroy healthy tissue.

The American Society for Laser Medicine and Surgery, Inc. urges that: (1) All operative areas should be equipped with oxygen and other drugs and equipment required for cardiopulmonary resuscitation (CPR). (2) Non-physicians performing laser procedures should be properly trained, licensed, and insured. (3) A qualified and experienced supervising physician should be able to respond to and manage unanticipated events or other emergencies within five minutes of the time they occur. (4) Emergency transportation to a hospital or other acute-care facility should be available whenever laser surgery is performed in a non-hospital setting.

Preparation

Because laser surgery is used to treat so many dissimilar conditions, the patient should ask his physician for detailed instructions about how to prepare for a specific procedure. Diet, activities, and medications may not have to be limited prior to surgery, but some procedures require a physical examination and a medical history that: determines the patient’s general health and current medical status; describes how the patient has responded to other illnesses, hospital stays, and diagnostic or therapeutic procedures; and clarifies what the patient expects the outcome of the procedure to be.

Aftercare

Most laser surgeries can be performed on an outpatient basis, and patients are usually permitted to leave the hospital or medical office when their vital signs have stabilized. A patient who has been sedated should not be discharged: until he/she has recovered from the anesthesia and knows who and where he/she is; and unless the patient is accompanied by a responsible adult.

The doctor may prescribe analgesic (pain-relieving) medication, and should provide easy-to-understand written instructions that describe how the patient’s recovery should progress and what to do in case complications or emergency arise.

Risks

Like traditional surgery, laser surgery can be complicated by: hemorrhage, infection, or perforation (piercing) of an organ or tissue.

Laser surgery can also involve risks that are not associated with traditional surgical procedures. Being careless or not practicing safe surgical techniques can severely burn the patient’s lungs or even cause them to explode. Patients must wear protective eye shields while undergoing laser surgery on any part of the face near the eyes or eyelids, and the U.S. Food and Drug Administration (FDA) has said that both doctors and patients must use special protective eyewear whenever a CO₂ laser is used.

Laser beams can burn or destroy healthy tissue, cause injuries that are painful and sometimes permanent, and actually compound problems they are supposed to solve. Errors or inaccuracies in laser surgery can worsen a patient’s vision, for example, and lasers can scar and even change the skin color of some patients.

Normal results

The nature and severity of the problem, the skill of the surgeon performing the procedure, and the patient’s general health and realistic expectations are among the factors that influence the outcome of laser surgery.

Successful procedures can enable patients to: feel better; look younger; and enjoy longer, fuller, more active lives.

A patient who is considering any kind of laser surgery should ask his doctor to provide detailed information about what the outcome of the surgery is expected to be, what the recovery process will

KEY TERMS

Argon —A colorless, odorless gas.

Astigmatism —Irregular curvature of the cornea causing distorted images.

Canker sore —A blister-like sore on the inside of the mouth that can be painful but is not serious.

Carbon dioxide —A heavy, colorless gas that dissolves in water.

Cardiopulmonary resuscitation —An emergency procedure used to restore circulation and prevent brain death to a person who has collapsed, is unconscious, is not breathing, and has no pulse.

Cauterize —To use heat or chemicals to stop bleeding, prevent the spread of infection, or destroy tissue.

Cornea —The outer, transparent lens that covers the pupil of the eye and admits light.

Endometriosis —An often painful gynecologic condition in which endometrial tissue migrates from the inside of the uterus to other organs inside and beyond the abdominal cavity.

Glaucoma —A disease of the eye in which increased pressure within the eyeball can cause gradual loss of vision.

Invasive surgery —A form of surgery that involves making an incision in the patient’s body and inserting instruments or other medical devices into it.

Nearsightedness —A condition in which one or both eyes cannot focus normally, causing objects at a distance to appear blurred and indistinct. Also called myopia.

Ovarian cyst —A benign or malignant growth on an ovary. An ovarian cyst can disappear without treatment or become extremely painful and have to be surgically removed.

Vaporize —To dissolve solid material or convert it into smoke or gas.

Varicose veins —Swollen, twisted veins, usually occurring in the legs, that occur more often in women than in men.

involve, and how long it will probably be before he/she regains a normal appearance and can resume his/her normal activities.

Abnormal results

A person who is considering any type of laser surgery should ask his/her doctor to provide specific and detailed information about what could go wrong during the procedure and what the negative impact on the patient’s health or appearance might be.

Lighter or darker skin may appear, for example, when a laser is used to remove Sun damage or age spots from an olive-skinned or dark-skinned individual. This abnormal pigmentation may or may not disappear in time.

Scarring or rupturing of the cornea is uncommon, but laser surgery on one or both eyes can: increase sensitivity to light or glare; reduce night vision; permanently cloud vision; or cause sharpness of vision to decline throughout the day.

Signs of infection following laser surgery include: burning, crusting of the skin, itching, pain, scarring, and severe redness.

Laser beams can burn or destroy healthy tissue, cause injuries that are painful and sometimes permanent, and actually compound problems they are supposed to solve. Errors or inaccuracies in laser surgery can worsen a patient’s vision, for example, and lasers can scar and even change the skin color of some patients. Laser surgery is sometimes performed under general anesthesia. The risks of general anesthesia should be discussed with the anesthesiologist before the surgical procedure.

The amount of convalescence and recovery time will vary depending on the pre-existing health and condition of the patient and the type of surgery performed. The time necessary for convalescence and recovery can be generally determined based on these specific factors, and should be discussed with the medical team before the surgery.

Resources

BOOKS

Chang, William Shen-chie. Principles of Lasers and Optics. Cambridge, UK, and New York: Cambridge University Press, 2005.

Csele, Mark. Fundamentals of Light Sources and Lasers. Hoboken, NJ: J. Wiley, 2004.

Hitz, C. Breck. Introduction to Laser Technology. New York: IEEE Press, 2001.

Keller, Gregory, et al. Lasers in Aesthetic Surgery. New York: Thieme Medical Pub., 2001.

Nair, K.P. Raiappan. Atoms, Molecules, and Lasers. Oxford, UK: Alpha Science, 2006.

Vij, D.F., and K. Mahesh, eds. Medical Applications of Lasers. Boston, MA: Kluwer Academic, 2002.

Waynant, Ronald W., ed. Lasers in Medicine. Boca Raton, FL: CRC Press, 2002.

PERIODICALS

Alster, Tina S. “Update on Dermatologic Laser Surgery: New Trends for 2002.” Cosmetic Dermatology 15, no. 2 (2002): 33-37.

Kronberger, C. “The Veterinary Technician’s Role In Laser Surgery.” Veterinary Clinics of North America 32, no. 3 (2002): 723-735.

Maureen Haggerty

Laser Posterior Capsulotomy

Definition
Purpose
Demographics
Description
Diagnosis/Preparation
Aftercare
Risks
Normal results
Morbidity and mortality rates
Alternatives

Definition

Laser posterior capsulotomy, or YAG laser capsulotomy, is a noninvasive procedure performed on the eye to remove the opacification (cloudiness) that develops on the posterior capsule of the lens of the eye after extraction of a cataract. This differs from the anterior capsulotomy that the surgeon makes during cataract extraction to remove a cataract and implant an intraocular lens (IOL). Laser posterior capsulotomy is performed with Nd:YAG laser, which uses a wavelength to disrupt the opacification on the posterior lens capsule. The energy emitted from the laser forms a hole in the lens capsule, removing a central area of the opacification. This posterior capsule opacification (PCO) is also referred to as a secondary cataract.

PCO formation is an attempt by the eye to make a new lens from remaining lens material. One form of PCO is a fibrosis that forms inside the capsule by lens epithelial (outer lining) cells that migrate from the anterior capsule to the posterior capsule when the anterior lens capsule is opened to remove the primary cataract and insert the IOL. Opacification is also be formed by residual lens cortex cells. The epithelial cells can transform into myofibroblasts and proliferate; myofibroblasts are precursors to muscle cells and capable of contraction. The deposit of collagen on these cells leaves the posterior lens capsule with a white, fibrous appearance. This type of opacification can appear within days of cataract surgery. The greatest capsule opacification is found around the edges of the IOL, where the anterior and posterior lens capsules adhere and form a seam, called Soem-mering’s ring.

Elschnig’s pearls are a proliferation of cells on the outside of the capsule. This type of PCO can be several layers thick and develops months to years after cataract surgery. Elschnig’s pearls can also appear along the margins of a previously performed laser capsulotomy.

A secondary cataract will also form from wrinkling of the lens capsule, either secondary to contraction of the myofibroblasts on the capsule or because of stretching of the capsule by haptics, or hooks, used to hold the IOL in place.

Posterior capsule opacification is the most common complication of cataract removal or extraction. It does not occur when an anterior chamber lens is implanted, because in this procedure the capsule is usually extracted along with the cataract, and a lens is attached to the iris in the front part of the eye, called the anterior chamber. This technique for cataract removal is not often performed.

Purpose

The purpose of a laser capsulotomy is to remove a PCO. This procedure dramatically improves visual acuity and contrast sensitivity and decreases glare. The visual acuity before capsulotomy can be as poor as 20/400, but barring any other visual or ophthalmologic conditions, the patient will see as well after a laser posterior capsulotomy as after removal of the original

KEY TERMS

Anterior chamber— The part of the eye located behind the cornea and in front of the iris and lens; it is filled with aqueous fluid.

Cataract— An opacification of the lens in the eye. There are three types of cataracts: subcapsular, which forms inside the capsule in which the lens is located; nuclear, which is a natural yellowing of the lens nucleus; cortical, which refers to spoke-type opacities within the cortex layer of the lens.

Lens capsule— The “bag” is a membrane that holds the lens in place and holds a posterior lens implant when a cataract is removed.

Macula— This is the part of the retina in which the highest concentration of photoreceptors are found.

Posterior capsule opacification (PCO)— This refers to the opacities that form on the back of the lens capsule after cataract removal or extraction. It is synonymous with a secondary cataract.

Posterior chamber— This is the part of the eye located behind the lens of the eye and includes the retina, where the photoreceptors are located.

Vitreous— This is the jelly-like substance that fills the space between the lens capsule and the retina.

cataract. Laser capsulotomies are usually performed once a patient’s vision is 20/30.

Demographics

Approximately 20% of patients who undergo cataract extraction with placement of an intraocular lens into the posterior lens capsule will eventually undergo a laser capsulotomy, although a PCO may appear in up to 50% of patients who have undergone cataract surgery. The average time after cataract extraction for this procedure to be performed is two years, but it may be performed as early as three months after cataract removal, or as late as five years afterward.

Patients who fall into groups with an increased incidence of a secondary cataract formation have an increased rate of YAG capsulotomy. Patients who are younger when undergoing cataract removal are more likely to develop a PCO than are geriatric patients. This is particularly true of pediatric patients who are experiencing ocular growth. The incidence of PCO is higher in women than in men. Fifty percent of patients who experience papillary, or iris capture, of the IOL, which occurs if the IOL moves through the pupil (a hole in the iris) from its position in the posterior chamber of the eye to the anterior chamber, will form a PCO and benefit from laser capsulotomy.

The degree and incidence of capsule opacification also varies with the type of implant used in the initial cataract operation. Larger implants are associated with decreased opacification, and round-edged silicone implants are associated with a greater incidence of opacification than are acrylic implants, which have a square-edged design. These two types of IOLs are called foldable implants because they unfold after being placed in the eye, allowing for a smaller incision on the front of the eye during cataract surgery. Also, the incidence of PCO is less with a silicone IOL than with a rigid IOL. The greater the amount of remaining lens material after extraction, especially in the area of Soemmering’s ring, the greater the probability of PCO formation and laser capsulotomy. Also, diabetic patients are more likely to require a YAG capsulotomy than are non-diabetic patients. This is especially true for YAG capsulotomies performed on diabetics 18 months or later after cataract removal. The extent of diabetic retinopathy does not correlate with incidence of PCO or laser capsulotomy. Finally, insufficient dilation of the pupil during cataract surgery and inexperience of the surgeon doing cataract removal contribute to an increased risk of secondary cataract formation.

Description

Laser capsulotomy is usually performed in an ophthalmologist’s office as an outpatient procedure. Before beginning the capsulotomy, the patient is given an informed consent for the procedure. An hour before the laser capsulotomy, a drop of a pressure-lowering drug such as timoptic or apraclonidine is administered. A weak dilating drop to enlarge the pupil is applied to the eye. The eye may be anesthetized locally if the doctor uses a special contact lens for the procedure.

The patient then puts the head in the chinrest of a slit lamp microscope, to which a laser is attached. The doctor then may place a special lens on the front of the eye. It is important that the patient remain still as the doctor focuses on the posterior capsule. A head strap to help keep the patient’s head in place may be used. While focusing on the posterior capsule, the doctor, with repeated bursts from the Nd:Yag laser in a circular manner, disrupts the PCO. An opening forms on the posterior part of the lens capsule as part of the PCO falls off of the posterior capsule and into the vitreous. Another drop of apraclonidine, or other pressure-lowering eyedrop, is applied to the eye as a preventative measure for increased pressure in the eye, which is experienced by most patients after the procedure. This is a brief procedure lasting only a few minutes and is not associated with pain.

Diagnosis/Preparation

Prior to performing a posterior capsulotomy, the doctor will perform a thorough ophthalmic examination and review any systemic medical problems. The ophthalmologic includes evaluation of visual acuity, slit-lamp biomicroscope examination of the eye to assess the extent and type of opacification and rule out inflammation or swelling in the front of the eye, measurement of intraocular pressure, and a thorough evaluation of the fundus or back of the eye to check for retinal detachments and macular problems, which would limit the extent to which the YAG capsulotomy could improve vision. A potential acuity meter (PAM) may be used to ascertain best expected visual acuity after YAG capsulotomy, and brightness acuity testing will determine the extent of glare experienced by the patient. Contrast sensitivity testing is employed by some doctors.

This procedure cannot be performed in the presence of certain preexisting ophthalmologic conditions. For example, irregularities of the cornea would interfere with the ability of the doctor to see the posterior capsule. Also, a laser capsulotomy could not be performed if there is ongoing inflammation in the eye, or if swelling of the macula (a part of the retina) is present. A laser capsulotomy would be contraindicated with glass IOLs. If macular edema is suspected, which can occur in up to 30% of patients who have undergone cataract surgery, a test called a fluoroscein angiography may also be performed.

Aftercare

After a laser capsulotomy, the patient will remain in the office for one to four hours so that the pressure in the eye can be evaluated. The patient can then resume normal everyday activities. After surgery, pressure-lowering eyedrops may be used for a week if the intraocular pressure is raised significantly. Cycloplegic agents to keep the pupil dilated and to prevent spasm of the muscles in the iris, and steroids to reduce inflammation may also be prescribed for up to a week. Follow-up visits are scheduled at one day, one week, one month, three months, and six months after capsulotomy.

Risks

One risk of laser capsulotomy is damage to the intraocular implant. Factors that determine the extent of damage to the IOL include the inherent resistance of a particular IOL to damage by the laser, the amount of energy used in the procedure, the position of the IOL within the lens capsule, and the focusing accuracy of the surgeon. The thicker the opacification of the lens capsule, the greater the amount of energy needed to remove it. The accuracy of the surgeon is improved when there is less opacification on the lens capsule.

In addition, during laser capsulotomy, the IOL can be displaced into the eye’s vitreous. This happens more often in eyes with a rigid implant, rather than with acrylic or silicone IOLs, and also if a larger implant is used. If the posterior capsule ruptures during extraction of the primary cataract, risk of lens displacement is also increased. Displacement risk is also increased if the area over which the laser capsulotomy is done is large. The most serious complication of a capsulotomy is IOL damage so extensive that extraction would be required. This is a rare complication.

Another risk of this surgery is the re-formation of Elschnig’s pearls over the opening created by the capsulotomy. This occurs in up to 80% of patients within two years of laser capsulotomy. Most of time, these PCOs will resolve over time without treatment, but 20% of patients will require a second laser capsulotomy. This secondary opacification by Elschnig pearls represents a spatial progression of the opacification that caused the initial secondary cataract.

Other risks to take into account when considering a posterior capsulotomy are macular edema, macular holes, corneal edema, inflammation of the iris, retinal detachment, and increased pressure in the eye, as well as glaucoma. These risks escalate with increased laser energy and with increased size of the capsulotomy area. Retinal detachments are usually treated with removal of the vitreous behind the lens capsule. Macular edema is treated by application of topical anti-inflammatory drops or intraocular steroid injections. Steroids control iritis (inflammation of the iris), either topically or intraocularly. Macular holes are also treated by removal of the vitreous (the substance that fills the main area of the eyeball), followed by one to three weeks of facedown positioning. Elevated intraocular pressure and glaucoma are treated with anti-glaucoma drops or glaucoma surgery, if necessary.

Finally, increased glare at night may result when the size of the capsulotomy is smaller than the diameter of the pupil during dark conditions.

Normal results

Within one to two days after surgery, maximum visual acuity will be attained by almost 99% of patients.

WHO PERFORMS THE PROCEDURE AND WHERE IS IT PERFORMED?

The procedure is usually performed in the office of an ophthalmologist or an osteopathic physician. The training of an ophthalmologist includes a year of internship and at least three years of residency training in the treatment of eye diseases and in eye surgery after graduation from medical school. In states where doctors of optometry are permitted by law to use lasers, and if trained in laser surgery, an optometrist may do the laser capsulotomy. A co-managing optometrist may perform some of the preoperative testing and postoperative follow-up.

Once the opacification is removed, most patients will not need a change in spectacle prescription. However, patients who have undergone implantation of a rigid IOL may experience an increase in hyperopia, or farsightedness, after a capsulotomy. For a few weeks after surgery, the presence of visual floaters, which are pieces of the excised capsule, is normal. But, the presence of floaters months after this timeframe, especially if accompanied by flashes of light, may signal a retinal tear or detachment and require immediate attention. Also, if vision suddenly or gradually worsens after an initial improvement, further follow-up to determine the cause of a decrease in visual function is imperative.

Morbidity and mortality rates

The probability of a retinal detachment after capsulotomy is 1.6-1.9%. This represents a two-fold increase of retinal detachment over the rate for all patients undergoing cataract surgery, regardless if a posterior capsulotomy was done or not. Macular edema occurs in up to 2.5% of patients who undergo a laser capsulotomy and is more likely to occur when the capsulotomy is performed soon after cataract extraction, or in younger individuals. Rarely does glaucoma develop after laser capsulotomy, although as many as two-thirds of patients will experience transient increased intraocular pressure.

Alternatives

The alternative to laser capsulotomy is surgical capsulotomy of the PCO and the adjacent anterior vitreous. There is an increased risk of retinal detachment when this invasive intraocular surgery is employed. The other alternative is to leave the PCO in place. This leaves the patient with permanent decreased visual acuity.

QUESTIONS TO ASK THE DOCTOR

• What are the alternatives to laser capsulotomy?
• Am I a good candidate for this procedure?
• What will my vision be like after the procedure?
• How many of these procedures have you performed?

Resources

BOOKS

Albert, Daniel M., M.D. Ophthalmic Surgery Principles and Techniques. Oxford, England: Blackwell Science, 1999.

Albert, Daniel M., M.D., and Frederick A. Jakobiec. Principles and Practice of Ophthalmology 2nd ed. Philadelphia, PA: W. B. Saunders Company, 2000.

Albert, Daniel, M. and Mark J. Lucarelli, MD. Clinical Atlas of Procedures in Ophthalmic Surgery 1st ed. Chicago, IL: American Medical Association Press, 2003.

Azuara-Blanco, Augusto, M.D, Ph.D., et. al. Handbook of Glaucoma. 1st ed. London, England: Taylor & Francis, 2007.

Ritch, Robert, M. D., et. al. The Glaucomas. St. Louis, MO: 1996.

Gills, James P. Cataract Surgery: The State of the Art. Thorofare, NJ: Slack Inc., 1997.

Jaffe, Norman. Atlas of Ophthalmic Surgery. London: Mosby-Wolfe, 1996.

Steinert, Roger F. Cataract Surgery: Technique, Complications, & Management. 2nd ed. Philadelphia, PA: W. B. Saunders, 2003.

PERIODICALS

Baratz, K. H., et al. “Probability of Nd:YAG Laser Capsulotomy After Cataract Surgery in Olmsted County, Minnesota.” American Journal of Ophthalmology 131 (February 2001): 161–166.

Charles, Steve. “Vitreoretinal Complications of YAG Laser Capsulotomy.” Ophthalmology Clinics of North America 14 (December 2001): 705–9.

Chua, C. N, et al. “Refractive Changes following Nd:YAG Capsulotomy.” Eye 15 (June 2001): 303–5.

Hayashi, Ken. “Posterior Capsule Opacification After Surgery In Patients With Diabetes Mellitus.” American Journal of Ophthalmology 134 (July 2002): 10–16.

Hu, Chao-Yu., et al. “Change in the Area of Laser Posterior Capsulotomy: 3 Month Follow-Up.” Journal of Cataract and Refractive Surgery 27 (April 2001): 537–42.

Kurosaka, Daijiro, et al. “Elschnig Pearl Formation Along the Neodymium:YAG Laser Posterior Capsulotomy Margin.” Journal of Cataract and Refractive Surgery 28 (October 2002): 1809–1813.

O’Keefe, Michael, et al. “Visual Outcomes and Complications of Posterior Chamber Intraocular Lens

Implantation in the First Year of Life.” Journal of Cataract and Refractive Surgery 27 (December 2001): 2006–11.

Sundelin, Karin, and Johan Sjostrand. “Posterior Capsule Opacification 5 Years After Extracapsular Cataract Extraction.” Journal of Cataract and Refractive Surgery 25 (February 1999): 246–50.

Trinavarant, A., et al. “Neodymium: YAG laser Damage Threshold of Foldable Intraocular Lenses.” Journal of Cataract and Refractive Surgery 27 (May 2001): 775–880.

ORGANIZATIONS

American Academy of Ophthalmology. P. O. Box 7424, San Francisco, CA 94120-7424. (415) 561-8500. http://www.aao.org.

Canadian Ophthalmological Society (COS). 610-1525 Carling Avenue, Ottawa ON K1Z 8R9 Canada. http://www.eyesite.ca>.

National Eye Institute. 2020 Vision Place, Bethesda, MD 20892-3655. (301) 496-5248. http://nei.nih.gov.

Prevent Blindness America. 500 East Remington Road, Schaumburg, IL 60173. (800) 331-2020. http://www.preventblindness.org.

Wills Eye Hospital. 840 Walnut Street, Philadelphia, PA 19107. (215) 928-3000. http://www.willseye.org.

OTHER

“Lasers in Eye Surgery.” http://www.karger.ch/gazette/64/kohnen/art_5_2.htm

“Narrow Angle Glaucoma and Acute Angle Closure Glaucoma.” http://www.M.D.eyedocs.com/edacuteglaucoma.htm

National Cancer Institute (NCI) Physician Data Query (PDQ). Intraocular (Eye) Melanoma: Treatment, January 2, 2003 [cited April 2, 2003]. http://www.nci.nih.gov/cancerinfo/pdq/treatment/intraocularmelanoma/healthprofessional.

National Eye Institute (NEI). Facts About Glaucoma. 2008. NIH Publication No. 99–651. http://www.nei.nih.gov/health/glaucoma/glaucoma_facts.asp.

Waheed, Nadia K., and C. Stephen Foster. “Melanoma, Iris.” eMedicine, July, 2005 [cited April 2, 2003]. http://www.emedicine.com/oph/topic405.htm.

Martha Reilly, OD

Laura Jean Cataldo, RN, EdD

Laser Surgery

Definition

Laser (light amplification by stimulated emission of radiation) surgery uses an intensely hot, precisely focused beam of light to remove or vaporize tissue and control bleeding in a wide variety of non-invasive and minimally invasive procedures.

Purpose

Laser surgery is used to:

• Cut or destroy tissue that is abnormal or diseased without harming healthy, normal tissue
• Shrink or destroy tumors and lesions
• Cauterize (seal) blood vessels to prevent excessive bleeding.

Precautions

Anyone who is thinking about having laser surgery should ask his doctor to:

• Explain why laser surgery is likely to be more beneficial than traditional surgery
• Describe his experience in performing the laser procedure the patient is considering.

Because some lasers can temporarily or permanently discolor the skin of Blacks, Asians, and Hispanics, a dark-skinned patient should make sure that his surgeon has successfully performed laser procedures on people of color.

Some types of laser surgery should not be performed on pregnant women or on patients with severe cardiopulmonary disease or other serious health problems.

Description

The first working laser was introduced in 1960. The device was initially used to treat diseases and disorders of the eye, whose transparent tissues gave ophthalmic surgeons a clear view of how the narrow, concentrated beam was being directed. Dermatologic surgeons also helped pioneer laser surgery, and developed and improved upon many early techniques and more refined surgical procedures.

Types of lasers

The three types of lasers most often used in medical treatment are the:

• Carbon dioxide (CO₂) laser. Primarily a surgical tool, this device converts light energy to heat strong enough to minimize bleeding while it cuts through or vaporizes tissue.
• Neodymium:yttrium-aluminum-garnet (Nd:YAG) laser. Capable of penetrating tissue more deeply than other lasers, the Nd:YAG makes blood clot quickly and can enable surgeons to see and work on parts of the body that could otherwise be reached only through open (invasive) surgery.
• Argon laser. This laser provides the limited penetration needed for eye surgery and superficial skin disorders. In a special procedure known as photodynamic therapy (PDT), this laser uses light-sensitive dyes to shrink or dissolve tumors.

Laser applications

Sometimes described as "scalpels of light," lasers are used alone or with conventional surgical instruments in a diverse array of procedures that:

• improve appearance
• relieve pain
• restore function
• save lives

Laser surgery is often standard operating procedure for specialists in:

• cardiology
• dentistry
• dermatology
• gastroenterology (treatment of disorders of the stomach and intestines)
• gynecology
• neurosurgery
• oncology (cancer treatment)
• ophthalmology (treatment of disorders of the eye)
• orthopedics (treatment of disorders of bones, joints, muscles, ligaments, and tendons)
• otolaryngology (treatment of disorders of the ears, nose, and throat)
• pulmonary care (treatment of disorders of the respiratory system
• urology (treatment of disorders of the urinary tract and of the male reproductive system)

Routine uses of lasers include erasing birthmarks, skin discoloration, and skin changes due to aging, and removing benign, precancerous, or cancerous tissues or tumors. Lasers are used to stop snoring, remove tonsils, remove or transplant hair, and relieve pain and restore function in patients who are too weak to undergo major surgery. Lasers are also used to treat:

• angina (chest pain)
• cancerous or non-cancerous tumors that cannot be removed or destroyed
• cold and canker sores, gum disease, and tooth sensitivity or decay
• ectopic pregnancy (development of a fertilized egg outside the uterus)
• endometriosis
• fibroid tumors
• gallstones
• glaucoma, mild-to-moderate nearsightedness and astigmatism, and other conditions that impair sight
• migraine headaches
• non-cancerous enlargement of the prostate gland
• nosebleeds
• ovarian cysts
• ulcers
• varicose veins
• warts
• numerous other conditions, diseases, and disorders

Advantages of laser surgery

Often referred to as "bloodless surgery," laser procedures usually involve less bleeding than conventional surgery. The heat generated by the laser keeps the surgical site free of germs and reduces the risk of infection. Because a smaller incision is required, laser procedures often take less time (and cost less money) than traditional surgery. Sealing off blood vessels and nerves reduces bleeding, swelling, scarring, pain, and the length of the recovery period.

Disadvantages of laser surgery

Although many laser surgeries can be performed in a doctor's office rather than in a hospital, the person guiding the laser must be at least as thoroughly trained and highly skilled as someone performing the same procedure in a hospital setting. The American Society for Laser Medicine and Surgery, Inc. urges that:

• All operative areas be equipped with oxygen and other drugs and equipment required for cardiopulmonary resuscitation (CPR)

• Non-physicians performing laser procedures be properly trained, licensed, and insured
• A qualified and experienced supervising physician be able to respond to and manage unanticipated events or other emergencies within five minutes of the time they occur
• Emergency transportation to a hospital or other acute-care facility be available whenever laser surgery is performed in a non-hospital setting.

Imprecisely aimed lasers can burn or destroy healthy tissue.

Preparation

Because laser surgery is used to treat so many dissimilar conditions, the patient should ask his physician for detailed instructions about how to prepare for a specific procedure. Diet, activities, and medications may not have to be limited prior to surgery, but some procedures require a physical examination and a medical history that:

• Determines the patient's general health and current medical status
• Describes how the patient has responded to other illnesses, hospital stays, and diagnostic or therapeutic procedures
• Clarifies what the patient expects the outcome of the procedure to be.

Aftercare

Most laser surgeries can be performed on an outpatient basis, and patients are usually permitted to leave the hospital or medical office when their vital signs have stabilized. A patient who has been sedated should not be discharged:

• Until he has recovered from the anesthesia and knows who and where he is
• Unless he is accompanied by a responsible adult.

The doctor may prescribe analgesic (pain-relieving) medication, and should provide easy-to-understand written instructions that describe how the patient's recovery should progress and what to do in case complications or emergency arise.

Risks

Like traditional surgery, laser surgery can be complicated by:

• hemorrhage
• infection
• perforation (piercing) of an organ or tissue

Laser surgery can also involve risks that are not associated with traditional surgical procedures. Being careless or not practicing safe surgical techniques can severely burn the patient's lungs or even cause them to explode. Patients must wear protective eye shields while undergoing laser surgery on any part of the face near the eyes or eyelids, and the United States Food and Drug Administration (FDA) has said that both doctors and patients must use special protective eyewear whenever a CO₂ laser is used.

Laser beams can burn or destroy healthy tissue, cause injuries that are painful and sometimes permanent, and actually compound problems they are supposed to solve. Errors or inaccuracies in laser surgery can worsen a patient's vision, for example, and lasers can scar and even change the skin color of some patients.

Normal results

The nature and severity of the problem, the skill of the surgeon performing the procedure, and the patient's general health and realistic expectations are among the factors that influence the outcome of laser surgery. Successful procedures can enable patients to:

• feel better
• look younger
• enjoy longer, fuller, more active lives

A patient who is considering any kind of laser surgery should ask his doctor to provide detailed information about what the outcome of the surgery is expected to be, what the recovery process will involve, and how long it will probably be before he regains a normal appearance and can resume his normal activities.

Abnormal results

A person who is considering any type of laser surgery should ask his doctor to provide specific and detailed information about what could go wrong during the procedure and what the negative impact on the patient's health or appearance might be.

KEY TERMS

Argon— A colorless, odorless gas.

Astigmatism— A condition in which one or both eyes cannot filter light properly and images appear blurred and indistinct.

Canker sore— A blister-like sore on the inside of the mouth that can be painful but is not serious.

Carbon dioxide— A heavy, colorless gas that dissolves in water.

Cardiopulmonary resuscitation— An emergency procedure used to restore circulation and prevent brain death to a person who has collapsed, is unconscious, is not breathing, and has no pulse.

Cauterize— To use heat or chemicals to stop bleeding, prevent the spread of infection, or destroy tissue.

Cornea— The outer, transparent lens that covers the pupil of the eye and admits light.

Endometriosis— An often painful gynecologic condition in which endometrial tissue migrates from the inside of the uterus to other organs inside and beyond the abdominal cavity.

Glaucoma— A disease of the eye in which increased pressure within the eyeball can cause gradual loss of vision.

Invasive surgery— A form of surgery that involves making an incision in the patient's body and inserting instruments or other medical devices into it.

Nearsightedness— A condition in which one or both eyes cannot focus normally, causing objects at a distance to appear blurred and indistinct. Also called myopia.

Ovarian cyst— A benign or malignant growth on an ovary. An ovarian cyst can disappear without treatment or become extremely painful and have to be surgically removed.

Vaporize— To dissolve solid material or convert it into smoke or gas.

Varicose veins— Swollen, twisted veins, usually occurring in the legs, that occur more often in women than in men.

Lighter or darker skin may appear, for example, when a laser is used to remove sun damage or age spots from an olive-skinned or dark-skinned individual. This abnormal pigmentation may or may not disappear in time.

Scarring or rupturing of the cornea is uncommon, but laser surgery on one or both eyes can:

• increase sensitivity to light or glare
• reduce night vision
• permanently cloud vision, or cause sharpness of vision to decline throughout the day

Signs of infection following laser surgery include:

• burning
• crusting of the skin
• itching
• pain
• scarring
• severe redness
• swelling

Resources

ORGANIZATIONS

American Society for Dermatologic Surgery. 930 N. Meacham Road, P.O. Box 4014, Schaumburg, IL 60168-4014. (847) 330-9830. 〈http://www.asds-net.org〉.

American Society for Laser Medicine and Surgery. 2404 Stewart Square, Wausau, WI 54401. (715) 845-9283. 〈http://www.aslms.org〉.

Cancer Information Service. 9000 Rockville Pike, Building 31, Suite 10A18, Bethesda, MD 20892. 1-800-4-CANCER. 〈http://wwwicic.nci.nih.gov〉. 7.

National Cancer Institute. Building 31, Room 10A31, 31 Center Drive, MSC 2580, Bethesda, MD 20892-2580. (800) 422-6237. 〈http://www.nci.nih.gov〉.