Farsightedness
Farsightedness
EVIDENCE AND REMEDIES OF HYPEROPIA
Our religions, mythologies, and fables admonish us to overcome temptation, exercise self-discipline, and heed the future—consider Adam and Eve, Odysseus, and the Ant and the Grasshopper. Social scientists too offer helpful strategies for increasing willpower and avoiding indulgence (e.g., Ainslie 1975; Trope and Fishbach 2000; Wertenbroch 1998). The seemingly universal espousal of prudence and farsightedness as noble goals is reflected in the voluminous literature in the social sciences on self-control. This body of research is premised on the notion that people are shortsighted (myopic) and easily tempted by hedonic “sins,” such as overbuying (oniomania), splurging on tasty but unhealthy food, and indulging in luxuries (see, e.g., Prelec and Herrnstein 1992; Thaler 1980).
An alternative research paradigm challenges the universality of myopia and proposes that people often suffer from a reverse self-control problem, namely excessive farsightedness (“hyperopia”) and overcontrol (Kivetz and
Simonson 2002b; Kivetz and Keinan 2006; Keinan and Kivetz 2007). Such hyperopia leads people to deprive themselves of indulgence and instead overly focus on acting responsibly, delaying gratification, and doing “the right thing.” Research on farsightedness examines the underlying processes (e.g., guilt, justification), the way people cope with hyperopia (e.g., by precommitting to indulgence), and the consequences of overcontrol (e.g., long-term regret).
Ran Kivetz and Yuhuang Zheng (2006) shed light on the antecedents of hyperopia by highlighting the role of justification and guilt in self-control decisions (see also Kivetz and Simonson 2002a). Building on prior analyses in the social sciences, they propose two complementary routes to justifying self-gratification: the first through hard work or excellent performance (an entitlement justification) and the second through the attainment of indulgence without depleting income or monetary resources. Consistent with the two routes to justification, it is demonstrated that (1) higher required effort enhances preference for indulgence rewards over more prudent necessities, but a reverse effect is observed when the interchangeability of effort and income is implied; (2) providing (bogus) excellence feedback on an effort task enhances choices of indulgence, unless the interchangeability of effort and income is suggested; and (3) sensitivity to effort and excellence (i.e., justification) cues is greater for individuals who experience stronger (chronic or manipulated) guilt.
EVIDENCE AND REMEDIES OF HYPEROPIA
Kivetz and Itamar Simonson (2002b) provide a more direct examination of the notion of excessive farsightedness and the strategies that people use to overcome this (reverse) self-control problem. They found that a large segment of people perceive themselves as having insufficient indulgence and seek ways to correct this imbalance in their lives. Such people force themselves to indulge in an attempt to avoid default forms of spending on utilitarian necessities and/or savings. In particular people who have difficulty choosing items that are perceived as indulgences or luxuries (e.g., a cruise) over necessities (e.g., saving for college education) and cash in everyday decisions use precommitments to future hedonic experiences. For example, a substantial segment of people choose hedonic luxury awards over cash of equal or greater value (the choices and incentives are real). People explain such choices based on the need to precommit to indulgence, to make sure that the award does not end up in the pool of money used for necessities.
Kivetz (2007) provides additional direct evidence for the concept of hyperopia (excessive farsightedness). It is shown that people select pleasurable vices when the consequences of their decisions are psychologically distal (e.g., temporally delayed, hypothetical, improbable, abstract, or self-irrelevant) but reverse their decisions when the consequences are psychologically proximal (e.g., temporally imminent, real, vivid, or self-relevant). These reversals are more pronounced among people with a chronic tendency to experience guilt.
CONSEQUENCES OF HYPEROPIA
Kivetz and Anat Keinan (2006) investigate the consequences of hyperopia for people’s well-being and long-term feelings. The extant literature on self-control suggests that people not only yield to temptations they had originally planned to resist but also subsequently reverse their preferences and regret their myopic behaviors (e.g., Schelling 1992). Although yielding to temptation certainly can be harmful, Kivetz and Keinan argue that excessive farsightedness can also have negative long-term consequences. In particular they propose that with the passage of time, choices of virtue over vice (e.g., work over pleasure) increasingly evoke regret. Accordingly they demonstrate that increasing the temporal separation between the actual decision and its assessment enhances the regret (or anticipatory regret) of righteous choices. Building on research on self-control and on affect (e.g., Kivetz and Simonson 2002b; Kahneman 1995; Metcalfe and Mischel 1999), Kivetz and Keinan show that greater temporal perspective allows people to escape the influence of indulgence guilt and causes them to experience a wistful feeling of missing out on the pleasures of life.
A great deal of research in psychology, economics, marketing, and other social sciences has examined self-control and time inconsistency. Such research has relied on a myopic premise. Late-twentieth-century and early twenty-first-century research advances an alternative perspective, namely that of excessive farsightedness and over-control. By exploring what is essentially a reverse form of self-control, this research contributes to a fuller understanding of self-regulation as a dynamic and general process. Some key discoveries that are diametrically opposed to the myopic premise include:
the finding that people require special entitlement justifications (hard work, excellence) to indulge;
the finding that people are motivated to work harder for hedonic luxuries than cash equivalents but are willing to spend more money on the latter;
the finding that people perceive themselves as suffering from excessive farsightedness and consequently correct this imbalance in their lives by precommitting to future hedonic experiences;
the finding that people are more likely to precommit to indulgence and to select vice when the consequences of their decisions are psychologically distal (e.g., temporally delayed, hypothetical, or abstract);
the detrimental impact of excessive farsightedness on well-being in the long run; that is, righteous choices of virtue over vice give rise to increasing regret over time, and considering long-term regret motivates people to select indulgence and luxury; and the fact that the preceding findings are more pronounced among people who experience stronger (chronic or manipulated) indulgence guilt.
SEE ALSO Behavior, Self-Constrained; Saving Rate; Self-Control
BIBLIOGRAPHY
Ainslie, George. 1975. Specious Reward: A Behavioral Theory of Impulsiveness and Impulse Control. Psychology Bulletin 82 (April): 463–496.
Kahneman, Daniel. 1995. Varieties of Counterfactual Thinking. In What Might Have Been: The Social Psychology of Counterfactual Thinking, ed. Neal J. Roese and James M. Olson, 375–396. Mahwah, NJ: Erlbaum.
Keinan, Anat, and Ran Kivetz. 2007. Remedying Hyperopia: The Effects of Self-Control Regret on Consumer Behavior. Working paper, Columbia University.
Kivetz, Ran. 2007. Hyperopia: A Theory of Reverse Self-Control. Working paper, Columbia University.
Kivetz, Ran, and Anat Keinan. 2006. Repenting Hyperopia: An Analysis of Self-Control Regrets. Journal of Consumer Research 33 (September): 273–282.
Kivetz, Ran, and Itamar Simonson. 2002a. Earning the Right to Indulge: Effort as a Determinant of Customer Preferences toward Frequency Program Rewards. Journal of Marketing Research 39 (2): 155–170.
Kivetz, Ran, and Itamar Simonson. 2002b. Self-Control for the Righteous: Toward a Theory of Pre-Commitment to Indulgence. Journal of Consumer Research 29 (2): 199–217.
Kivetz, Ran, and Yuhuang Zheng. 2006. Determinants of Justification and Self-Control. Journal of Experimental Psychology 135 (4): 572–587.
Metcalfe, Janet, and Walter Mischel. 1999. A Hot/Cool-System Analysis of Delay of Gratification: Dynamics of Willpower. Psychological Review 106 (1): 3–19.
Prelec, Drazen, and Richard J. Herrnstein. 1992. A Theory of Addiction. In Choice over Time, ed. George Loewnstein and Jon Elster. New York: Sage.
Schelling, Thomas C. 1992. Self-Command: A New Discipline. In Choice over Time, ed. George Loewenstein and Jon Elster, 167–176. New York: Sage.
Thaler, Richard. 1980. Toward a Positive Theory of Consumer Choice. Journal of Economic Behavior and Organization 1 (March): 39–60.
Trope, Yaacov, and Ayelet Fishbach. 2000. Counteractive Self-Control in Overcoming Temptation. Journal of Personality and Social Psychology 79: 493–506.
Wertenbroch, Klaus. 1998. Consumption Self-Control by Rationing Purchase Quantities of Virtue and Vice. Marketing Science 17 (4): 317–337.
Ran Kivetz
Hyperopia
Hyperopia
Definition
Hyperopia (farsightedness) is an eye condition in which incoming rays of light reach the retina before they converge into a focused image.
Description
When light passes through the lens and cornea of the eye, its velocity decreases. The surfaces of the lens and cornea are not perpendicular to the incoming light, so the direction of the light changes. The greater the curvature of the lens system, the greater the change in the direction of the light.
When parallel light rays pass through the lens system of the eye, they are bent so they converge at a point some distance behind the lens. With perfect vision, this point of convergence where the light rays are focused lies on the retina. Hyperopia is the condition in which the point of
focus of parallel light rays from an object lies behind the retina. This condition exists when the eyeball depth is too short for the curvature of its lens system.
There is a connection between the focusing of the lens of the eye (accommodation) and convergence of the eyes (the two eyes turning in to look at a close object). A good example is during reading, when the lens accommodates to make the close-up material clear and the eyes turn in to look at the print and keep it from doubling. Because of this connection between accommodation and convergence, if the lens needs to accommodate and focus for distance (to bring the image back onto the retina), the eyes may appear to turn in.
Causes & symptoms
Babies are generally born slightly hyperopic, but this symptom tends to decrease with age. There is normal variation in eyeball length and curvature of the lens and cornea, and some combinations of these variables give rise to eyes in which the cornea is too flat for the distance between the cornea and the retina. If the hyperopia is not too severe, the lens may be able to accommodate and bring the image back onto the retina. This accomodation results in clear distance vision, but the constant focusing could cause headaches or eyestrain. If the lens cannot accommodate for the full extent of the hyperopia, the distant image is blurry. If the eyes are focused for distance and the person is looking at a nearby object, the lens needs to accommodate further. This need may result in blurry nearby objects or headaches during close work.
Symptoms depend on the degree of hyperopia. Some individuals may have no symptoms, while others have blurry near vision and clear distance vision, and those with the most severe cases have blurry near and distance vision. Headaches and eyestrain may also occur, particularly when doing close work. An eye turned in (esotropia) may be a result of hyperopia, particularly in children. A turned eye could also signal a more serious problem, so a physician should be consulted.
Diagnosis
Because it is possible to have good visual acuity with some degree of hyperopia it, is important to relax accommodation before an eye exam. This is done with the use of eye drops and is called a cycloplegic exam, or cycloplegic refraction. The patient's visual status can be determined with a hand-held instrument called a retinoscope and/or by having the patient read from an eye chart while placing different lenses in front of the patient's eyes. The patient should be driven home after such an exam because the drops cause blurred vision for several hours.
Treatment
Herbals
Bilberry (Vaccinium myrtillus ) increases the flow of blood through the vessels of the eye. Eye drops of eyebright (Euphrasia officinalis ) tea can relieve eye-strain and, taken orally with rosemary (Rosemarinus officinalis ) in white wine, can improve vision. Schisandra (Schisandra chinensis ) improves visual clarity.
Homeopathy
Rue (Ruta graveolens ) can be prescribed for eye-strain. A homeopathic practitioner should be consulted for a proper recommendation.
Supplements
Vitamins A and C, magnesium , zinc, and selenium can help strengthen the retina and improve vision. Flavonoids—present in bilberry and eyebright—improve visual clarity.
Deconditioning
Persons whose vision changes according to their emotional state may have vision problems because of negative conditioning. Exploration and deconditioning may improve their vision.
Ayurveda
Head massage and nasya (placing drops in the nose) using warm Jivantal taila oil (which contains Asparagus racemosus, Glycyrrhiza glabra, Leptadenia reticulata, Sida cordifolia, Sida retusa, and sesame oil ) may improve vision in persons who are hyperopic.
Chinese medicine
Performing qiqong eye exercises significantly reduced hyperopia in children. In another study, children with hyperopia were cured following treatment with plum-blossom needle tapping plus external application of Huoxue Zengshi Ye (Infusion for Promoting Blood Circulation and Improving Eyesight) and Huoxue Zengshi Dan (Pellets for Promoting Blood Circulation and Improving Eyesight).
Bates method
The Bates method involves the use of therapeutic eye exercises to help strengthen and train the eye muscles. Some patients have found the eye exercises to help, although the method has not been tested in a clinical setting.
Other
Other movement exercises or disciplines can be useful including massage, Feldenkrais movement therapy, yoga and t'ai chi. A practitioner should be consulted to determine what would be most helpful for particular individuals.
Allopathic treatment
The usual treatment for hyperopia is corrective lenses (spectacles or contact lenses). Special contact lenses (vision orthotics) that are worn overnight temporarily re-shape the cornea for ideal vision on the following day.
There are now several different surgical methods used to correct hyperopia. One approach is to implant corrective contact lenses behind the patient's iris. Another approach, called laser in situ keratomileusis (LASIK), is to surgically increase the curvature of the eye's existing cornea or lens using a laser. Many surgeries are successful, but complications, including worsening of vision, may occur.
In mid-2002, the Food and Drug Administration (FDA) approved a new surgical technique to correct hyperopia. Called conductive keratoplasty, it involves no cutting or removal of tissue. An ophthalmologist uses a small probe about the size of a human hair to pass radiofrequency waves that produce heat into the corneal tissue. The waves shrink the tissue and reshape the cornea.
Expected results
The prognosis for fully corrected vision is excellent for patients with low to moderate degrees of hyperopia. Patients with very high hyperopia may not achieve full correction.
Hyperopia increases the chances of chronic glaucoma, but vision loss from glaucoma is preventable.
Prevention
Hyperopia is usually present at birth and cannot be prevented. Eyestrain may be prevented by resting the eyes when they become overworked, blinking often, and periodically changing the eyes' focus while driving or doing close work for extended periods of time.
Resources
BOOKS
Newell, Frank W. Ophthalmology: Principles and Concepts. 8th edition. St. Louis: Mosby, 1996.
PERIODICALS
"Eye Zapper for Hyperopia." Chemistry and Industry (May 6, 2002):7.
"Eyes Wide Open About LASIK." Harvard Health Letter 24 (October 1999): 1+.
Hongfeng, Cheng and Ma Yuying. "Treatment of Juvenile Ametropia by Auricular-Plaster Therapy Combined with Plum-Blossom Needle Tapping: A Report of 200 Cases." Journal of Traditional Chinese Medicine 18 (1998): 47–48.
Lieberath, Frederik. "High Tech Eyes." Harper's Bazaar (September 1999): 529+.
Preboth, Monica. "FDA Approves Surgical Device to Treat Farsightedness." American Family Physician (June 1, 2002): 2389.
ORGANIZATIONS
American Academy of Ophthalmology. PO Box 7424, San Francisco, CA 94120-7424. (415) 561-8500. http://www.eyenet.org/.
American Optometric Association. 243 North Lindbergh Boulevard, St. Louis, MO 63141. (800) 365-2219. http://www.aoanet.org/.
OTHER
Edmiston, D. "Hyperopia." ://eyeinfo.com/hyperopia.html/. "Treating Vision Disorders." AlternativeMedicine.com. http://www.alternativemedicine.com
Belinda Rowland
Teresa G. Odle
Hyperopia
Hyperopia
Definition
Hyperopia (farsightedness) is the condition of the eye where incoming rays of light reach the retina before they converge into a focused image.
Description
When light goes through transparent but dense material like the materials of the eye's lens system (the lens and cornea), its velocity decreases. If the surface of the dense material is not perpendicular to the incoming light, as is the case with the curved surfaces on lenses and corneas, the direction of the light changes. The greater the curvature of the lens system, the greater the change in the direction of the light.
When parallel light rays from an object go through the lens system of the eye, they are bent so they converge at a point some distance behind the lens. With perfect vision this point of convergence, where the light rays are focused, is on the retina. This happens when the cumulative curvature of the lens plus cornea and the distance from the lens to the retina are just right for each other. The condition where the point of focus of parallel light rays from an object is behind the retina is called hyperopia. This condition exists when the combined curvature of the lens and cornea is insufficient (e.g., flatter than needed for the length of the eyeball). This condition can be equivalently described by saying hyperopia exists when the eyeball is too short for the curvature of its lens system.
There is a connection between the focusing of the lens of the eye (accommodation) and convergence of the eyes (the two eyes turning in to point at a close object). The best example is during reading. The lens accommodates to make the close-up material clear and the eyes turn in to look at the print and keep it single. Because of this connection between accommodation and convergence, if the lens needs to accommodate to focus for distance (to bring the image back onto the retina) the eyes may appear to turn in even when looking at the distance. This can cause a condition known as accommodative esotropia in children. The eyes turn in and the cause is accommodation because of hyperopia.
Causes and symptoms
Babies are generally born slightly hyperopic. This tends to decrease with age. There is normal variation in eyeball length and curvature of the lens and cornea. Some combinations of these variables give rise to eyes where the cornea is too flat for the distance between the cornea and the retina. If the hyperopia is not too severe the lens may be able to accommodate and bring the image back onto the retina. This would result in clear distance vision, but the constant focusing might result in headaches or eyestrain. If the lens cannot accommodate for the full amount of the hyperopia the distance image would be blurry.
If the eyes are focusing for distance and now the person is looking at a near object, the eyes need to accommodate further. This may result in blurry near objects or headaches during near work.
Depending upon the amount of hyperopia, symptoms can range from none to clear distance vision but blurry near vision, to blurry distance and near vision. Headaches and eyestrain may also occur, particularly when doing near tasks. An eye turned in (esotropia) may be a result of hyperopia, particularly in children. However, because a turned eye may be a result of more serious causes it is very important to have it checked out.
Diagnosis
Because it is possible to have good visual acuity with some degree of hyperopia it is important to relax accommodation before the eye exam. This is done with the use of eyedrops and is called a cycloplegic exam or cycloplegic refraction. The drops relax the accommodation (thus making reading blurry until the drops wear off). Patients will usually be asked to have someone drive them home because of the blurriness. The doctor can then determine the patient's visual status with a hand-held instrument called a retinoscope and/or have the patient read from an eye chart while placing different lenses in front of the patient's eyes. Refractive error is measured in units called diopters (D).
Treatment
The usual treatment for hyperopia is corrective lenses (spectacles or contact lenses).
KEY TERMS
Cornea— The clear, dome-shaped outer covering of the front of the eye. It lies in front of the iris and pupil.
Iris— The colored ring just behind the cornea and in front of the lens that controls the amount of light sent to the retina.
Pupil— The black hole in the center of the iris. Light enters here on the way to the lens and retina.
Refraction— Method of determining the optical status of the eyes. Lenses are placed before the patient's eyes while reading from an eye chart. The result is the eyeglass or contact lens prescription.
Retina— The inner, light-sensitive layer of the eye containing rods and cones; transforms the image it receives into electrical messages sent to the brain via the optic nerve.
Different surgical methods to correct hyperopia are under investigation. One approach is to implant corrective contact lenses behind the patient's iris. The first experimental implantable contact lenses were implanted in 1997. Another approach is to surgically increase the curvature of the eye's existing cornea or lens. Although there have been many reports of success using different kinds of lasers to increase corneal curvature, as of 1998 there are still problems with stability and predictability. The introduction of light-activated biologic tissue glue in 1997 holds promise for improvements in those areas.
Prognosis
The prognosis for fully corrected vision is excellent for patients with low to moderate amounts of hyperopia. Patients with very high hyperopia (+10.00D or more) may not achieve full correction. Moreover, surgery to correct hyperopia will probably be perfected and approved in the near future.
Hyperopia increases the chances of chronic glaucoma, but vision loss from glaucoma is preventable.
Prevention
Hyperopia is usually present at birth, and there is no known way to prevent it.
Resources
ORGANIZATIONS
American Academy of Ophthalmology. 655 Beach Street, PO Box 7424, San Francisco, CA 94120-7424. 〈http://www.eyenet.org〉.
American Optometric Association. 243 North Lindbergh Blvd., St. Louis, MO 63141. (314) 991-4100. 〈http://www.aoanet.org〉.
OTHER
Edmiston, Dave. "Hyperopia." Lasikpatient.org. 〈http://www.lasikpatient.org〉.
Hyperopia
Hyperopia
Definition
Hyperopia, also known as hypermetropia or far-sightedness, is the condition of the eye in which incoming rays of light reach the retina before they converge into a focused image.
Description
When light goes through the lens and cornea, its velocity decreases. The greater the curvature of the lens system, the greater the change in the direction of the light. When parallel light rays from an object go through the lens system, they are bent so they converge at a point some distance behind the lens. With perfect vision this point of convergence is on the retina. Hyperopia is the condition in which the point of focus of parallel light rays from an object is behind the retina. This condition exists when the combined curvature of the lens and cornea is insufficient (e.g., flatter than needed for the length of the eyeball).
There is a connection between the focusing of the lens of the eye (accommodation) and convergence of the eyes (the two eyes turning in to point at a close object). The best example is during reading. The lens accommodates to bring close-up material into focus and the eyes turn in to view the print and keep it single. Because of this connection between accommodation and convergence, the eyes may appear to turn in if the lens needs to accommodate to focus, even on distant objects. This can result in a condition known as accommodative esotropia. The eyes turn in and the cause is accommodation because of hyperopia.
Causes and symptoms
Most babies are born slightly hyperopic. This tends to decrease with age. In some eyes the cornea is too flat for the distance between the cornea and the retina. If the hyperopia is not too severe the lens may accommodate and focus the image onto the retina. This results in clear distance vision, also potential headaches or eyestrain. If the lens cannot accommodate for the full amount of the hyperopia, the distance image would be blurry.
If the eyes are focusing for distance and the patient shifts his or her gaze to a near object, the eyes need to accommodate further. This may result in nearby objects appearing blurry, or the patient may experience headaches while performing work on objects that are close to the eyes.
Symptoms can range widely depending on the severity of hyperopia. There may be no noticeable symptoms, distance vision may be clear but near vision blurry, or both distance and near vision may be blurry. Headaches and eyestrain may occur, particularly when performing near tasks. An eye turned in (esotropia) may be a result of hyperopia, particularly in children.
Diagnosis
To determine hyperopia, a complete eye exam should be performed by an ophthalmologist (M.D.) or optometrist (O.D.). The exam should begin by the physician or ophthalmic assistant taking a detailed medical history from the patient. Then the physician, or in some cases a highly trained ophthalmic assistant, will begin the ocular examination by measuring the visual acuity and performing a refraction.
During the exam the physician will also determine ocular motility and alignment, nearpoint of convergence, near fusional vergence amplitudes, relative accommodation measurements, accommodative amplitude, and facility of accommodation. Additional ocular health assessment and screenings should rule out other accommodative dysfunctional disorders such as Graves' disease.
Treatment
The usual treatment for hyperopia is corrective lenses (eyeglasses or contact lenses ). Plus-powered spherical or spherocylindrical lenses are prescribed. In some instances, physicians will choose pharmaceuticals to reduce a high accommodative convergence to accommodation.
In June 2000, the Food and Drug Administration (FDA) approved the first laser treatment for hyperopia. Laser thermal keratoplasty (LTK), performed by an M.D., takes three seconds per eye and involves no cutting or removal of corneal eye tissue. The holium:YAG laser uses a process for shrinking collagen and applies two concentric rings of eight simultaneous spots of laser energy to the periphery of the cornea. The laser heats the corneal collagen and steepens its shape, improving refractive (focusing) power.
LTK patients must be at least 40 years old; have stable vision for at least six months; fall in the low-to-moderate range of hyperopia (+0.75 diopters to +2.50 diopters); and have no more than 0.75 diopters of astigmatism. A complete medical history must be taken before the procedure is performed. Patients who fall into any of the following categories should not have LTK performed:
- pregnant or nursing women
- patients with clinically significant corneal dystrophy or scarring in the 6 mm or 7 mm central zone
- patients with a history of herpetic keratitis
- patients with an autoimmune disease, collagen vascular disease, clinically significant atopic syndrome, insulin dependent diabetes or an immune compromised status
Investigation of phakic intraocular lenses to treat hyperopia continues. As of early 2001, there were three separate FDA clinical trials in progress. The most promising is an implantable contact lens to treat hyperopia that is injected through a clear corneal incision.
In conjunction with these treatments, physicians may also want to address environmental factors to treat hyperopia, and advise patients to reduce glare and improve lighting and ergonomic conditions in their work stations.
Prognosis
Patients with low to moderate amounts of hyperopia have an excellent opportunity to receive fully corrected vision with eyeglasses, contact lenses or refractive surgery. Patients with very high hyperopia (+10.00D or more) may not achieve full correction.
Hyperopia increases the chances of chronic glaucoma, but vision loss from glaucoma is preventable.
Health care team roles
Nursing and allied health professionals perform an important role in the examination to determine hyperopia. They take a detailed patient history, insert eyedrops, and ready the physician's instruments. Skilled technicians also can perform the first level of refraction in the general eye exam. Depending on the technician's skill level, the physician may check these findings. Technology also allows technicians to perform parts of the exam previously only completed by the eye doctor, including corneal topography, retinal photography, and automated keratometry.
Ophthalmic assistants and nurses also assist in the screening of LTK patients. They prep the patients for surgery and may insert anesthetic eyedrops.
KEY TERMS
Accommodation— The ability of the eyes to focus clearly at various distances.
Cornea— The clear, dome-shaped outer covering of the front of the eye. It lies in front of the iris and pupil.
Iris— The colored ring just behind the cornea and in front of the lens that controls the amount of light sent to the retina.
Pupil— The black hole in the center of the iris. Light enters here on the way to the lens and retina.
Refraction— Method of determining the optical status of the eyes. Lenses are placed before the patient's eyes while reading from an eye chart. The result is the eyeglass prescription.
Retina— The inner, light-sensitive layer of the eye containing rods and cones; transforms the image it receives into electrical messages sent to the brain via the optic nerve.
Prevention
Hyperopia is usually present at birth, and there is no known way to prevent it.
Resources
BOOKS
Newell, Frank W. Ophthalmology: Principles and Concepts, 8th edition. St. Louis: Mosby, 1996.
ORGANIZATIONS
American Academy of Ophthalmology. PO Box 7424, San Francisco, CA 94120-7424. (415) 561-8500. 〈http://www.eyenet.org〉.
American Optometric Association. 2420 North Lindbergh Boulevard, St. Louis, MO 63141. (800) 365-2219. 〈http://www.aoanet.org〉.
OTHER
Edmiston, D. "Hyperopia." 〈http://www.eyeinfo.com/hyperopia.html〉.
"New technologies continue to expand options for treating keratoconus, myopia, hyperopia." Primary Care Optometry News 〈http://www.slackinc.com/eye/pcon/200101/newtec.asp〉.
"Optometric Clinical Practice Guideline Care of the Patient with Hyperopia." American Optometric Association Online〈http://www.aoanet.org〉.
Roach, Linda. "Correcting Hyperopia: Make Way for LTK." EyeNet Magazine Online〈http://www.eyenet.org/eyenet_mag/02_01/refract.html〉.
Sabbagh, Leslie. "Phakic IOLs Gaining Ground." Review of Ophthalmology Online〈http://www.revophth.com/2001/January/January01PhakicTrial.htm〉.
Farsightedness
Farsightedness
How Do Doctors Diagnose and Treat Farsightedness?
Farsightedness is an eye disorder that causes objects that are close to a person to appear out of focus or blurry, while objects at a distance may seem clear.
KEYWORDS
for searching the Internet and other reference sources
Hyperopia
Ophthalmology
Optometry
Vision
To people with farsightedness, the words on this page would seem blurry, unless they were wearing prescription (pre-SKRIP-shun) eyeglasses or contact lenses designed to correct the problem. But if they looked up from the page to read a sign across the room, they probably could read it easily.
What Is Farsightedness?
In most cases, farsightedness occurs when the eyeball is shorter than normal. For an object to appear clear, the light passing through the eye must focus on the retina, a layer of photosensitive* cells on the back of the eye. The retina is something like the film in a camera. It is where the image passing through the eye is projected and then sent along the optic nerve* to the brain. In the brain, the image is “developed” into what we see. If the eyeball is too short, the image that is projected onto the retina by close objects is blurred, and the person is said to be farsighted.
- * photosensitive
- means responsive to light
- * optic nerve
- is the nerve that sends messages, or conducts impulses, from the eye to the brain, making it possible to see. The optic nerve is also referred to as the second cranial nerve.
People with farsightedness usually have the disorder from birth. It is probably inherited from parents, although just because a parent is far-sighted does not mean the child necessarily will develop the problem too. Babies and younger children often are able to adapt to the problem. Muscles around the eyeball can change its shape, which makes it longer and allows the image to be focused properly on the retina. But as a child gets older, the muscles cannot do as good a job changing the eyeball’s shape, and images close up are out of focus.
How Do Doctors Diagnose and Treat Farsightedness?
It can take many years for the symptoms of farsightedness to become noticeable. Eventually, people with farsightedness notice problems while reading or seeing objects that are close, whereas things that are farther away remain clear. They also may start to get headaches after reading or doing other close work, and they may feel as if their eyes are tired.
Ophthalmologists* can diagnose farsightedness and correct it easily with prescription eyeglasses or contact lenses. These change the focus of the images passing into the eye so they are projected properly onto the retina. Surgery to correct the problem is available, but it is not as widely used as surgery to correct nearsightedness.
- * ophthalmologist
- (off-thal-MOLL-o-jist) is a medical doctor who specializes in treating diseases of the eye.
Presbyopia
Many people become more farsighted as they age. They develop a condition known as presbyopia (pres-be-O-pe-a), which is
Latin for “old eyes,” that causes close objects to appear out of focus. Presbyopia results because the lens at the front of the eyeball becomes thicker and less flexible as a person ages. This causes the eye to have trouble clearly focusing the images passing through the lens. The first sign of presbyopia may be noticed when adults pass age 40. They start to find they cannot read the newspaper as well. It is one reason one hears people joke that their arms are too short, because they try holding the paper or book farther away so they can see it clearly. People with farsightedness may need stronger prescription eyeglasses once they pass age 40. People with nearsightedness may need bifocal* or multifocal lenses.
- * bifocal
- or multifocal (progressive) lenses are prescription eyeglasses that have lenses divided into two or more sections. The bottom section allows a person to see things clearly that are close, and the top section allows a person to see things clearly that are far away
See also
Nearsightedness
Presbyopia
Resources
The U.S. National Eye Institute posts a resource list of eye health-related publications and organizations at its website. http://www.nei.nih.gov/publications/sel-org.htm
American Academy of Ophthalmology, P.O. Box 67424, San Francisco, CA 94120-7424. The American Academy of Ophthalmology website includes a search engine that locates information about many disorders of the eye. Telephone 415-561-8500 http://www.eyenet.org