Topics

Visual Acuity: What is 20/20 Vision?

Visual acuity is only one in a series of factors that evaluate one's vision. 20/20 vision is a term used to express normal visual acuity (the clarity or sharpness of vision) measured at a distance of 20 feet. If you have 20/20 vision, you can see clearly at 20 feet what should normally be seen at that distance. If you have 20/100 vision, it means that you must be as close as 20 feet to see what a person with normal vision can see at 100 feet. 20/20 does not necessarily mean perfect vision. 20/20 vision only indicates the sharpness or clarity of vision at a distance. There are other important vision skills, including peripheral awareness or side vision, eye coordination, depth perception, focusing ability and color vision that contribute to your overall visual ability. Some people can see well at a distance, but are unable to bring nearer objects into focus. This condition can be caused by hyperopia (farsightedness) or presbyopia (loss of focusing ability). Others can see items that are close, but cannot see those far away. This condition may be caused by myopia (nearsightedness).

A comprehensive eye examination by a doctor of optometry can diagnose those causes, if any, that are affecting your ability to see well. In most cases, your optometrist can prescribe glasses, contact lenses or a vision therapy program that will help improve your vision. If the reduced vision is due to an eye disease, the use of ocular medication or other treatment may be used.

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Myopia (Nearsightedness)

People with myopia have difficulty seeing objects further away. Nearsightedness, or myopia, as it is medically termed, is a vision condition in which near objects are seen clearly, but distant objects do not come into proper focus. Nearsightedness occurs if your eyeball is too long or the cornea has too much curvature, so the light entering your eye is not focused correctly.

Nearsightedness is a very common vision condition that affects nearly 30 percent of the U.S. population. Some evidence supports the theory that nearsightedness is hereditary. There is also growing evidence that nearsightedness may be caused by the stress of too much close vision work. It normally first occurs in school-age children. Because the eye continues to grow during childhood, nearsightedness generally develops before age 20.

A sign of nearsightedness is difficulty seeing distant objects like a movie or TV screen or chalkboard. A comprehensive optometric examination will include testing for nearsightedness. Your optometrist can prescribe eyeglasses or contact lenses to optically correct nearsightedness by altering the way the light images enter your eyes. You may only need to wear them for certain activities, like watching TV or a movie or driving a car, or they may need to be worn for all activities.

Refractive surgery or laser procedures are also possible treatments for nearsightedness as is orthokeratology. Orthokeratology (ortho-k) is a non-invasive procedure that involves the wearing of a series of specially-designed rigid contact lenses to progressively reshape the curvature of the cornea over time.

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Hyperopia (Farsightedness)

People with hyperopia have difficulty seeing closer objects. Farsightedness, or hyperopia, as it is medically termed, is a vision condition in which distant objects are usually seen clearly, but close ones do not come into proper focus. Farsightedness occurs if your eyeball is too short or the cornea has too little curvature, so light entering your eye is not focused correctly.

Common signs of farsightedness include difficulty in concentrating and maintaining a clear focus on near objects, eye strain, fatigue and/or headaches after close work, aching or burning eyes, irritability or nervousness after sustained concentration. Common vision screenings, often done in schools, are generally ineffective in detecting farsightedness. A comprehensive optometric examination will include testing for farsightedness. In mild cases of farsightedness, your eyes may be able to compensate without corrective lenses. In other cases, your optometrist can prescribe eyeglasses or contact lenses to optically correct farsightedness by altering the way the light enters your eyes.

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Presbyopia

Presbyopia is a natural part of the aging process of the eye. Presbyopia is a vision condition in which the crystalline lens of your eye loses its flexibility, which makes it difficult for you to focus on close objects. Presbyopia may seem to occur suddenly, but the actual loss of flexibility takes place over a number of years. Presbyopia usually becomes noticeable in the early to mid-40s. Presbyopia is a natural part of the aging process of the eye. It is not a disease, and it cannot be prevented. Some signs of presbyopia include the tendency to hold reading materials at arm's length, blurred vision at normal reading distance and eye fatigue along with headaches when doing close work. A comprehensive optometric examination will include testing for presbyopia.

To help you compensate for presbyopia, your optometrist can prescribe reading or computer glasses, bifocals, progressive lenses (no-line bifocals) or bifocal contact lenses. Because presbyopia can complicate other common vision conditions like nearsightedness, farsightedness and astigmatism, your optometrist will determine the specific lenses to allow you to see clearly and comfortably. You may only need to wear your glasses for close work like reading, but you may find that wearing them all the time is more convenient and beneficial for your vision needs. Because the effects of presbyopia continue to change the ability of the crystalline lens to focus properly, periodic changes in your eyewear may be necessary to maintain clear and comfortable vision.

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Astigmatism

Those with mild astigmatism may experience headaches, eye strain, fatigue or blurred vision at certain distances.

Astigmatism is a vision condition that occurs when the front surface of your eye, the cornea, is slightly irregular in shape.This irregular shape prevents light from focusing properly on the back of your eye, the retina. As a result, your vision may be blurred at all distances. People with severe astigmatism will usually have blurred or distorted vision. Most people have some degree of astigmatism. A comprehensive optometric examination will include testing to diagnose astigmatism and determine the degree. Almost all levels of astigmatism can be optically corrected with properly prescribed and fitted eyeglasses and/or contact lenses. Corneal modification is also a treatment option for some patients.

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Amblyopia (Lazy Eye)

Early diagnosis increases the chance for a complete recovery. Lazy eye, or amblyopia, is the loss or lack of development of central vision in one eye that is unrelated to any eye health problem and is not correctable with lenses. It can result from a failure to use both eyes together. Lazy eye is often associated with crossed-eyes or a large difference in the degree of nearsightedness or farsightedness between the two eyes. It usually develops before the age of 6, and it does not affect side vision. Symptoms may include noticeably favoring one eye or a tendency to bump into objects on one side. Symptoms are not always obvious.

Treatment for lazy eye may include a combination of prescription lenses, prisms, vision therapy and eye patching. Vision therapy teaches the two eyes how to work together, which helps prevent lazy eye from reoccurring.

Early diagnosis increases the chance for a complete recovery. This is one reason why the American Optometric Association recommends that children have a comprehensive optometric examination by the age of 6 months and again at age 3. Lazy eye will not go away on its own. If not diagnosed until the pre-teen, teen or adult years, treatment takes longer and is often less effective.

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Strabismus (Crossed Eyes)

If detected and treated early, crossed-eyes can often be corrected with excellent results.

Strabismus occurs when one or both of your eyes turns in, out, up or down, and is usually caused by poor eye muscle control. This misalignment often first appears before age 21 months but may develop as late as age 6. This is one reason why the American Optometric Association recommends a comprehensive optometric examination before 6months and again at age 3. There is a common misconception that a child will outgrow strabismus. This is not true. In fact, the condition may get worse without treatment.

Treatment for strabismus may include single vision or bifocal eyeglasses, prisms, vision therapy, and in some cases, surgery. Vision therapy helps align your eyes and solves the underlying cause of strabismus by teaching your two eyes to work together. Surgery alone may straighten your eyes, but unless your eye muscle control is improved, your eyes may not remain straight. If detected and treated early, strabismus can often be corrected with excellent results.

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Color Deficiency

Color vision deficiency means that your ability to distinguish some colors and shades is less than normal. It occurs when the color-sensitive cone cells in your eyes do not properly pick up or send the proper color signals to your brain. About eight percent of men and one percent of women are color deficient.

Red-green deficiency is by far the most common form and it results in the inability to distinguish certain shades of red and green. Those with a less common type have difficulty distinguishing blue and yellow. In very rare cases, color deficiency exists to an extent that no colors can be detected, only shades of black, white and grey.

Because many learning materials are color-coded, it is important to diagnose color vision deficiency early in life. This is why the American Optometric Association recommends a comprehensive optometric examination before a child begins school.

Color vision deficiency is usually inherited and cannot be cured, but those affected can often be taught to adapt to the inability to distinguish colors. In some cases, a special red-tinted contact lens is used in one eye to aid people with certain color deficiencies.

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Eye Coordination

Eye coordination is a skill that must be developed. Eye coordination is the ability of both eyes to work together as a team. Each of your eyes sees a slightly different image and your brain, by a process called fusion, blends these two images into one three-dimensional picture. Good eye coordination keeps the eyes in proper alignment.  Poor eye coordination results from a lack of adequate vision development or improperly developed eye muscle control. Although rare, an injury or disease can cause poor eye coordination.

Because the images seen by each eye must be virtually the same, a person usually compensates for poor eye muscle control by subconsciously exerting extra effort to maintain proper alignment of the eyes. In more severe cases, the muscles cannot adjust the eyes so that the same image is seen and double vision occurs. Because the brain will try to avoid seeing double, it eventually learns to ignore the image sent by one eye. This can result in amblyopia, a serious vision condition commonly known as lazy eye.

Some signs and symptoms that may indicate poor eye coordination include double vision, headaches, eye and body fatigue, irritability, dizziness and difficulty in reading and concentrating. Children may also display characteristics that may indicate poor eye coordination including covering one eye, skipping lines or losing their place while reading, poor sports performance, avoiding tasks that require close work and tiring easily.

Becuase poor eye coordination can be difficult to detect, periodic optometric examinations, beginning at age 6 months and again at age 3 years are recommended. A comprehensive examination by a doctor of optometry can determine the extent, if any, of poor eye coordination. Poor eye coordination is often successfully treated with eyeglasses and/or vision therapy. The success rate for achieving proper eye coordination is quite high. Sometimes, eye coordination will improve when other vision conditions like nearsightedness or farsightedness are corrected. In some cases, surgery may be necessary.

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Children's Vision

• Infant's Vision
• Preschool Vision
• School-Age Children

Toys, Games, and Your Child's Vision

High-quality eye care can help enable your children to reach their highest potential.

Children with uncorrected vision conditions or eye health problems face many barriers in life ... academically ... socially ... and athletically. High-quality eye care can break down these barriers and help enable your children to reach their highest potential.

Vision doesn't just happen. A child's brain learns how to use eyes to see, just like it learns how to use legs to walk or a mouth to form words. The longer a vision problem goes undiagnosed and untreated, the more a child's brain learns to accommodate the vision problem.

That's why a comprehensive eye examination is so important for children. Early detection and treatment provide the very best opportunity to correct vision problems, so your child can learn to see clearly. Eighty percent of all learning is performed through vision. Make sure your child has the best possible tools to learn successfully.

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Corneal Modifications

• Ortho-K
• Refractive Surgery and Corneal Modification Definitions

Those interested in any of the corneal modifications should first have a comprehensive eye examination.

The cornea is the clear covering of the front of the eye that bends (or refracts) light rays as they enter the eye. For clear vision to occur, the cornea must have the correct shape and power to focus incoming light rays precisely on the retina at the back of the eye. If the cornea is too steep, too flat or irregular in shape, it cannot bend light at the angle needed to focus on the retina. As a result, eyeglasses or contact lenses may be needed to refract the incoming light rays at the angle needed for clear vision. In a nearsighted eye, for example, the cornea's shape causes incoming light rays to focus in front of the retina.

All corneal modification procedures are intended to alter the curvature of the cornea so that incoming light is refracted at an angle that allows it to focus precisely on the retina. This may eliminate the need for eyeglasses or contact lenses, or reduce the power of prescription lenses needed.

Those interested in any of the corneal modifications should first have a comprehensive eye examination to evaluate their eye health and determine their vision needs.

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CONTACT Lenses

• Facts and Stats
• Advantages and Disadvantages of Various Types of Contact Lenses
• Do's and Don'ts
• Contact Lenses and Cosmetics
• Monovision
• Signs of Potential Problems
• Cost of Contact Lenses
• Warning for Consumers: Popular Halloween Eye Wear Accessory Can Permanently Damage Eyes!
• Guidelines for The Use of Contact Lenses In Industrial Environments

Whether you already wear contact lenses or are considering them, this section serves as a primer. Facts and statistics about contact lens wearers, pointers for safe and successful use of contact lenses, and contact lenses and cosmetics are just a few of the topics covered here.

Getting started right with your contact lenses involves going to a doctor who provides full-service care. This includes a thorough eye examination, an evaluation of your suitability for contact lens wear, the lenses, necessary lens care kits, individual instructions for wear and care and unlimited follow-up visits over a specified time.

Facts and Stats

So you want to wear contact lenses. Well, you're not alone. Let’s take a quick look at who is wearing contact lenses today.

• Over 30 million Americans wear contact lenses
• Two-thirds of all contact lens wearers are female
• Ten percent are age 18 or under
• Fifteen percent are between the ages of 18-24
• 50 percent are 25 to 44 years old
• Most contact lens wearers are nearsighted
• Eighty percent wear daily wear soft lenses
• Over fifty percent wear 1 to 2-week disposable lenses
• Fifteen percent wear extended wear soft lenses
• Fifteen percent wear GP (gas permeable) lenses
• More than 80 percent of contact lens wearers go to an optometrist for their eye care.
• More than 97 percent of the practicing doctors of optometry offer contact lens services

Source: Contact Lens Institute
May 2003

Advantages and Disadvantages of Various Types of Contact Lenses

Reasons To Consider Contact Lenses

• Contact lenses move with your eye, allow a natural field of view, have no frames to obstruct your vision and greatly reduce distortions.
• They do not fog up, like glasses, nor do they get splattered by mud or rain.
• Contact lenses do not get in the way of your activities.
• Many people feel they look better in contact lenses.

Some Things To Remember About Contact Lenses

• Contact lenses, when compared with glasses, require a longer initial examination and more follow-up visits to maintain eye health; and more time for lens care.
• If you are going to wear your lenses successfully, you will have to clean and store them properly; adhere to lens wearing schedules; and make appointments for follow-up care.
• If you are wearing disposable or planned replacement lenses, you will have to carefully follow the schedule for throwing away used lenses.

Do's and Don'ts

Get started off right with your contact lenses by going to a doctor who provides full-service care. Full-service care may include the following items: a thorough eye examination, an evaluation of your suitability for contact lens wear, the lenses, necessary lens care kits, individual instructions for wear and care, and follow-up visits over a specified time. The initial visit and examination can take an hour or longer. Here is a list of other specific do's and don'ts to lead you to successful wear.

Do:

• Always wash your hands before handling contact lenses.
• Carefully and regularly clean contact lenses, as directed by your optometrist. If recommended, rub the contact lenses with fingers and rinse thoroughly with solution before soaking lenses overnight in sufficient multi-purpose solution to completely cover the lens.
• Store lenses in the proper lens storage case and replace the case at a minimum of every three months. Rinse the case after each use, keep it open and let it air dry between cleanings.
• Use only products recommended by your optometrist to clean and disinfect your lenses. Saline solution and rewetting drops are not designed to disinfect lenses.
• Only fresh solution should be used to clean and store contact lenses. Never re-use old solution. Contact lens solution must be changed according to the manufacturer's recommendations, even if the lenses are not used daily.
• Always follow the recommended contact lens replacement schedule prescribed by your optometrist.
• Remove contact lenses before swimming or entering a hot tub.
• See your optometrist for your regularly scheduled contact lens and eye examination.

Don't:

• Use cream soaps. They can leave a film on your hands that can transfer to the lenses.
• Put contact lenses in your mouth or moisten them with saliva, which is full of bacteria and a potential source of infection.
• Use homemade saline solutions. Improper use of homemade saline solutions has been linked with a potentially blinding condition among soft lens wearers.

Contact Lenses and Cosmetics

Here are some tips to help you wear your contacts and your cosmetics safely and comfortably together:

• Put on soft contact lenses before applying makeup.
• Put on rigid gas-permeable (RGP) lenses after makeup is applied.
• Avoid lash-extending mascara, which has fibers that can irritate the eyes, and waterproof mascara, which cannot be easily removed with water and may stain soft contact lenses.
• Remove lenses before removing makeup.
• Choose an oil-free moisturizer.
• Don’t use hand creams or lotions before handling contacts. They can leave a film on your lenses.
• Use hairspray before putting on your contacts. If you use hairspray while you are wearing your contacts, close your eyes during spraying and for a few seconds afterwards.
• Blink your eyes frequently while under a hair drier or blower to keep your eyes from getting too dry.
• Keep false eyelash cement, nail polish and remover, perfume and cologne away from the lenses. They can damage the plastic.
• Choose water-based, hypo-allergenic liquid foundations. Cream makeup may leave a film on your lenses.

Monovision

Monovision is a treatment technique that is often prescribed for people age 40 and older who are affected by presbyopia. Presbyopia occurs when, as part of the natural aging process, the eye’s crystalline lens loses its ability to bring close objects into clear focus.

Monovision means wearing a contact lens for near vision on one eye and, if needed, a lens for distance vision on the other eye. Most people who try monovision are able to adjust to it. Alternative treatments for presbyopia include a combination of contact lenses and reading glasses, or your doctor may also prescribe bifocal contact lenses.

Signs of Potential Problems

Problems with contact lens wear can be serious. It is generally not difficult to wear contact lenses. Following your doctor’s advice and regular follow-up care will prevent most problems. However, here is a list of some signs that things may not be going well. If you experience any of these, contact your optometrist as soon as possible.

• Blurred or fuzzy vision, especially of sudden onset.
• Red, irritated eyes.
• Uncomfortable lenses.
• Pain in and around the eyes.

Cost of Contact Lenses

Every optometrist individually determines his or her fees for services. There are a number of factors that may go into determining the initial cost of contact lenses, and these may include the professional services necessary to provide the best lens selection and a good start toward safe, successful wear. If you are considering contacts, be aware that some of the services and materials that might be included in the initial cost are:

• a thorough diagnostic examination
• a lens care kit
• lens wear and care training
• follow-up office visits over a specified period of time

If you already wear lenses and need replacements, or if you want a spare pair, the total cost might include the actual cost of the lenses plus the fee the doctor might charge for his or her professional time. Again, every optometrist individually determines his or her fees, and there is no formula or standard fee for contacts or professional services.
It is certainly important to check out costs when considering contacts, but cost is just one factor in making your decision. All types of lenses are not the same. It is important for you to get the lenses that are healthiest for you and the professional services and follow-up care to help you wear your lenses successfully.

Warning for Consumers: Popular Halloween Eye Wear Accessory Can Permanently Damage Eyes!

People who buy and wear contact lenses without medical guidance and a valid prescription put themselves at risk for serious, even blinding eye infections.

The American Optometric Association (AOA) is warning consumers about the risks of wearing decorative contact lenses sold without proper medical evaluation from a doctor of optometry and without a prescription.  These non-corrective lenses are easily accessible to consumers and are especially popular around Halloween.

Decorative lenses, also referred to as plano lenses, are marketed and distributed directly to consumers through a variety of sources, including flea markets, the Internet, beauty salons and convenience stores. Consumers often find them at retail outlets where they are sold as fashion accessories. 

“Buying contact lenses without a prescription can pose serious risk to your sight or eye health,” said Art Epstein, O.D., former chairman of the AOA Contact Lens and Cornea Section. “Decorative lenses, like their vision-correcting counterparts, require precise fitting and careful follow-up care.  Consumers purchasing these lenses from untrained individuals may receive poorly fitted or “demo” lenses and little to no instruction in proper lens care and cleaning.” 

People who buy and wear contact lenses without medical guidance and a valid prescription put themselves at risk for serious, even blinding eye infections.  A proper medical evaluation, ensures that the patient is an appropriate candidate for contact lens wear, that the lenses are properly fitted and that the patient is able to safely care for their lenses.

“While consumer education is important, it is equally imperative to ensure that laws are in place so that only people who are trained in the proper fitting and appropriate use of contacts are able to provide them to patients,” said Dr. Epstein.  “This is a serious public health issue, especially for adolescents and young adults,” he added.
“Consumers and retailers should understand that decorative lenses, like the contact lenses intended for correcting vision, present serious risks to eye health if they are distributed without the appropriate involvement of a qualified eye care professional,” added Dr. Epstein.

Other risks associated with use of decorative contact lenses include conjunctivitis, swelling, allergic reactions and corneal abrasion due to poor lens fit. Other problems may include reduced vision, glare, and other general eye and vision impairments.

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U/V Protection

• Sunglasses Shopping Guide

The principal danger posed by the sun is in the form of ultraviolet radiation, or for short, UV radiation. UV radiation is a component of solar energy, but it can also be given off by artificial sources like welding machines, tanning beds and lasers.

You are probably aware of the danger posed by UV radiation to your skin, but may not realize that exposure to UV radiation can harm your eyes and affect your vision as well.

There are three types of UV radiation. One type, called UV-C, is absorbed by the ozone layer and does not present any threat. That's not true of the other two types, UV-A and UV-B. More and more scientific evidence is showing that exposure to both UV-A and UV-B can have adverse long- and short-term effects on your eyes and vision. If you are exposed, unprotected, to excessive amounts of UV radiation over a short period of time, you are likely to experience an effect called photokeratitis.

Like a "sunburn of the eye" it may be painful and you may have symptoms including red eyes, a foreign body sensation or gritty feeling in the eyes, extreme sensitivity to light and excessive tearing. Fortunately, this is usually temporary and rarely causes permanent damage to the eyes.

Long-term exposure to UV radiation can be more serious. A number of scientific studies and research growing out of the U.S. space program have shown that exposure to small amounts of UV radiation over a period of many years may increase your chance of developing a cataract, and may cause damage to the retina, the nerve-rich lining of your eye that is used for seeing. The damage to the retina is usually not reversible.

The effects of UV radiation are cumulative. This means the longer your eyes are exposed to UV radiation, the greater the risk of developing such conditions as cataracts or macular degeneration in later life.

Researchers have not yet specifically determined how much exposure to UV radiation will cause how much damage, but a good recommendation is to wear quality sunglasses that offer good protection and a hat or cap with a wide brim whenever you are working outdoors, participating in outdoor sports, taking a walk, running errands or doing anything in the sun.

To provide protection for your eyes, your sunglasses should:

• block out 99 to 100 percent of both UV-A and UV-B radiation;
• screen out 75 to 90 percent of visible light;
• be perfectly matched in color and free of distortion and imperfection; and
• have lenses that are gray, green or brown.

Polycarbonate lenses are a must for your sunglasses if you participate in potentially eye hazardous work or sports. These lenses provide the most impact resistance. If you spend a lot of time outdoors in bright sunlight, wrap-around frames can provide additional protection from the harmful UV radiation.

Don't forget protection for children and teenagers. They typically spend more time in the sun than adults.
Be sure to see your doctor of optometry regularly [recommended schedule of examinations] for a thorough eye examination. It is a good way to monitor your eye health, maintain good vision, and keep track of your UV radiation protection needs as well as new advances in that protection.

UV Radiation Checklist

If one or more of the following factors fits you, you could be in a higher risk category for damage to eyes from UV radiation:

Much of the work performed in today's workplace relies on accurate vision to complete the task. However, work environments can be full of potential eye hazards. From eye strain to foreign objects, eye safety and protection are important considerations in many workplaces. These same hazards can come up while working and playing outside of the work environment.

In many cases, workers can make simple adjustments or use devices to help protect their eyes from potential hazards in the workplace. The AOA provides some helpful tips for workers who use computers, and work in industrial environments.

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Low Vision

• What Causes Low Vision?
• Common Types of Low Vision
• Low Vision Care
• Low Vision Exam
• Low Vision Devices
• Low Vision Rehabilitation

Low vision rehabilitation can help to make the most of remaining sight.

Few people are totally without sight. Most individuals today classified as "blind" actually have remaining sight and, thanks to developments in the field of low vision rehabilitation, can be helped to make good use of it, improving their quality of life.

Anyone with noncorrectable reduced vision is visually impaired, and can have a wide range of problems. The World Health Organization uses the following classifications of visual impairment. When the vision in the better eye with best possible glasses correction is:

• 20/30 to 20/60 is considered mild vision loss, or near-normal vision
• 20/70 to 20/160 is considered moderate visual impairment, or moderate low vision
• 20/200 to 20/400 is considered severe visual impairment, or severe low vision
• 20/500 to 20/1,000 is considered profound visual impairment, or profound low vision
• less than 20/1,000 is considered near-total visual impairment, or near total blindness
• no light perception is considered total visual impairment, or total blindness

There are also levels of visual impairment based on visual field loss (loss of peripheral vision). In the United States, any person with vision that cannot be corrected to better than 20/200 in the best eye, or who has 20 degrees or less of visual field remaining, is considered legally blind.

Visual impairments take many forms and exist in varying degrees.  It is important to understand that visual acuity alone is not a good predictor of the degree of problems a person may have. Someone with relatively good acuity (e.g., 20/40) can have difficulty functioning, while someone with worse acuity (e.g., 20/200) might not be having any real problems.

What Causes Low Vision?

Over 1.6 million older Americans are affected with Macular Degeneration.
Eye diseases or conditions may be responsible for visual impairment. Some of the more common causes include:

• Macular Degeneration – A disorder that affects the retina, the light sensitive lining at the back of the eye where images are focused. The macula—the area on the retina responsible for sharp central vision—deteriorates, causing blurred vision, which may cause problems such as difficulty reading, and for some, a blind spot in the central area of vision. The most common form of age-related macular degeneration is known as non-exudative, or "dry" form, which usually results in more slowly progressive vision loss. More rapid and severe vision loss comes from exudative, or the "wet" form, of macular degeneration, when abnormal blood vessels develop under the macula and leak fluid and blood. Both the exudative and the non-exudative forms of macular degeneration are age-related, and the leading cause of blindness in people over 50.  Recent studies estimate that over 1.6 million older Americans are affected. The exact cause is unknown. Although age is the primary contributing factor to the development of macular degeneration, cigarette smoking and nutrition can also play a role in the development of age-related macular degeneration.  There are also juvenile forms that are hereditary and also result in vision loss.
• Diabetic Retinopathy – Vision and/or visual functioning can fluctuate from day to day as a result of diabetes.  Diabetes can cause blood vessels that nourish the retina to develop tiny, abnormal branches that leak. This can interfere with vision and, over time, may cause severe damage to the retina.  Laser procedures and surgical treatments are used to reduce its progression, but systemic control of diabetes is a reputed factor.
• Retinitis Pigmentosa - Retinitis pigmentosa gradually destroys night vision, severely reduces side vision, and may result in total impairment. An inherited disease, it usually produces its first symptom—night blindness—in childhood or adolescence.
• Retinopathy of Prematurity (ROP) – Previously known as retrolental fibroplasia, retinopathy of prematurity occurs in infants born prematurely and is caused by high oxygen levels in incubators during the critical neonatal period.
• Retinal Detachment – Retinal detachment may result in total impairment in the detached area of the affected eye. It involves the retina separating from its underlying layer. Causes are holes in the retina, eye trauma, infection, blood vessel disturbance or a tumor. Through early diagnosis, most detached retinas can be surgically re-attached with partial to complete restoration of vision if surgery is performed in a timely fashion.
• Cataracts – A cataract is a clouding of part or all of the lens inside the eye. This clouding interferes with light reaching the retina at the back of the eye, resulting in a generalized loss of vision. Causes are aging, long-term exposure to the sun's ultraviolet radiation, injury, disease and inherited disorders. If the eye is healthy, a cataract can be surgically removed and vision restored, usually with intraocular lens implants. Cataract surgery has a high success rate in otherwise healthy eyes. However, there are still individuals for whom cataract surgery is not possible as well as those with other ocular diseases(s) that may require low vision rehabilitation to maximize the remaining vision.
• Glaucoma – Glaucoma is a form of damage to the optic nerve, which can result in vision impairment. The optic nerve damage in glaucoma can be due to the internal pressure in the eye building up because of problems with the flow or drainage of fluid within the eye, or can result without increased intraocular pressure (normal tension glaucoma) due to insufficient blood flow to the optic nerve. There are no early symptoms in the most common form, but the first signs of damage are side (peripheral) vision defects and difficulty with night vision. Early diagnosis and treatment with drugs or sometimes surgery can minimize vision loss.
• Acquired (Traumatic) Brain Injury - Vision can also be lost or damaged as a result of head injuries, brain damage and stroke. Signs and symptoms can include reduced visual acuity, visual field, or contrast sensitivity, blurred vision, eye misalignment, poor judgment of depth, glare sensitivity, confusion when performing visual tasks, difficulty reading, double vision, headaches, dizziness, abnormal body posture, and balance problems.

Common Types of Low Vision

• Loss of Central Vision – The loss of central vision creates a blur or blindspot, but side (peripheral) vision remains intact. This makes it difficult to read, recognize faces, and distinguish most details in the distance. Mobility, however, is usually unaffected because side vision remains intact.
• Loss of Peripheral (Side) Vision – Loss of peripheral vision is typified by an inability to distinguish anything to one side or both sides, or anything directly above and/or below eye level. Central vision remains, however, making it possible to see directly ahead. Typically, loss of peripheral vision may affect mobility and if severe, can slow reading speed as a result of seeing only a few words at a time. This is sometimes referred to as "tunnel vision."
• Blurred Vision – Blurred vision causes both near and far to appear to be out of focus, even with the best conventional spectacle correction possible.
• Generalized Haze – Generalized haze causes the sensation of a film or glare that may extend over the entire viewing field.
• Extreme Light Sensitivity – Extreme light sensitivity exists when standard levels of illumination overwhelm the visual system, producing a washed out image and/or glare disability. People with extreme light sensitivity may actually suffer pain or discomfort from relatively normal levels of illumination.
• Night Blindness – Night blindness results in inability to see outside at night under starlight or moonlight, or in dimly lighted interior areas such as movie theaters or restaurants.

Low Vision Care

Low Vision Rehabilitation is Treatment for Visual Impairment

Doctors of Optometry who specialize in low vision rehabilitation are skilled in the examination, treatment and management of patients with visual impairments not fully treatable by medical, surgical or conventional eyewear or contact lenses. Each type of low vision problem requires a different therapeutic approach. A thorough examination by an optometrist, which will also include tests to determine the patient's current vision status, will result in the development of a treatment plan.  Treatment plans may include prescription of glasses, specialized optical systems, therapeutic filters, non-optical options, and/or video magnification, and the prescription of rehabilitation therapy to effectively maximize visual functioning for activities of daily living.  Therapy may also be prescribed to enhance remaining visual skills and may also include referral to other vision rehabilitation professionals, as indicated.

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Sports & Vision

• Important Vision Skills for Sports

Eye protection should be a major concern to all athletes

Do you wish you could cut a few strokes off your golf score? Does your child always seem to be just a few steps away from the soccer ball? Having trouble returning your tennis partner's serve? Vision, just like speed and strength, is an important component in how well you play your sport.

And there is much more to vision than just seeing clearly. Your vision is composed of many interrelated skills that can affect how well you play your sport. However, just as exercise and practice can increase your speed and strength, it can also improve your visual fitness and accuracy.

Because all sports have different visual demands, an optometrist with expertise in sports vision can assess your unique visual system and recommend the proper eyeglasses or contact lenses, or design a vision therapy program to maximize your visual skills for your specific sport. Remember, a thorough eye examination by your doctor of optometry is a great place to begin "getting the winning edge."

Eye protection should also be a major concern to all athletes, especially in certain high-risk sports. Thousands of children and adults suffer sports-related eye injuries each year, and nearly all can be prevented by using the proper protective eyewear. Especially for sports played outdoors, appropriate sunglasses are a must, and some sport-specific designs may even help you improve your game. Ask your optometrist which type is best suited for your favorite.

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The data and images are adapted from the American Optometric Association website and the National Eye Institute website. 

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