Color Deficiency

What is color deficiency?
Color deficiency occurs when your ability to distinguish colors and shades is less than normal. The term "color blind" is often used, but usually incorrectly. Only a very small number of people are completely unable to identify any colors.

What causes color deficiency?
Color deficiency is usually inherited, but can also result from certain diseases, trauma or as a side effect of certain medications. It happens when the color-sensitive cone cells in the retina of your eye do not properly pick up or send to the brain correct color signals.

What types of color deficiency exist?
There are several. Red-green deficiency is by far the most common and results in the inability to distinguish between certain shades of red and green. In very rare cases, color deficiency exists to an extent that no colors can be detected. This person sees all things in shades of black, white and grey.

How is color deficiency detected?
People who are color deficient are generally unaware of their condition. They assume that everyone sees things the way they do. As a result, a complete optometric examination, including a test for color vision, is recommended. The test for color deficiency is a relatively simple one typically involving the viewing of a series of colored designs. The designs have been created in such a way that a person with normal color vision can see certain figures in the designs. A color deficient person will not be able to distinguish the figures.

When should a person be tested for color deficiency?
Every child should be checked for color deficiency by at least age five. It is important to detect color deficiency early because color-coded learning materials are used extensively in the primary grades. In addition, color deficiency may affect the career path of an individual, since the ability to distinguish colors is an important aspect of some jobs, such as pilots, electricians, some military personnel, police officers and others.

Can color deficiency be cured?
Unfortunately a cure for color deficiency has not yet been discovered. A person with color deficiency can, however, be taught to adapt to the inability to distinguish colors. For example, one can be taught to recognize the brightness and location of a traffic light rather than the color itself. It is also possible to increase the ability to distinguish colors with the use of special filters. A special red tinted contact lens, used in one eye, and other devices are used in some cases, to aid persons with certain color deficiencies.

This information was provided by the American Optometric Association (AOA). To find out more information visit their web site at www.aoanet.org/aoanet

What is amblyopia?
Amblyopia (lazy eye) is the loss or lack of development of vision in an eye that is unrelated to any eye health problem. The brain, for some reason, does not acknowledge the images seen by the amblyopic eye. Reduced vision due to amblyopia is not correctable with lenses alone.

Who is likely to develop amblyopia?
Amblyopia is generally the result of poor early visual development, and as such, usually occurs before the age of eight. Infants born prematurely or with low birth weight are at a greater risk for the development of the condition. It is estimated that two to four percent of children have amblyopia. The chance of amblyopia developing during adulthood is very small.

What causes amblyopia?
Amblyopia usually results from a failure to use both eyes together. It can be caused by the presence of strabismus (crossed-eyes), unequal refractive error (farsightedness or nearsightedness), or a physical obstruction of vision (cataract). If there is a large enough difference in the degree of nearsightedness, farsightedness or astigmatism between the two eyes, or if the eyes are crossed, the brain learns to ignore one image in favor of the other.

How does amblyopia affect vision?
Normally, the images sent by each eye to the brain are identical. When they differ too much, the brain learns to ignore the poor image sent by one eye and "sees" only with the good eye. The vision of the eye that is ignored becomes weaker from disuse.

Is the amblyopic eye blind?
The amblyopic eye is never blind in the sense of being entirely without sight. Amblyopia affects only the central vision of the affected eye. Peripheral awareness will remain the same.

What are the signs/symptoms of amblyopia?
Amblyopia usually produces few symptoms. It may be accompanied by crossed-eyes or a large difference in the refractive error between the two eyes. A child may also exhibit noticeable favoring of one eye and may have a tendency to bump into objects on one side.

How is amblyopia diagnosed?
A comprehensive optometric examination can determine the presence of amblyopia. The earlier it is diagnosed, the greater the chance for a successful treatment. Since amblyopia occurs only in one eye, the good eye takes over and the individual is generally unaware of the condition. That is why it is important to have your child's vision examined at about six months, at age three and again before he or she enters school.

How is amblyopia treated?
Corrective lenses, prisms and/or contact lenses are often used to treat amblyopia. Covering or occluding the better eye, either part-time or full-time, may be used to stimulate vision in the amblyopic eye. In addition, a program of vision therapy may be prescribed to help improve vision function.

Does amblyopia get worse?
Vision in the amblyopic eye may continue to decrease if left untreated. The brain simply pays less and less attention to the images sent by the amblyopic eye. Eventually, the condition stabilizes and the eye becomes virtually unused. It is quite difficult to effectively treat amblyopia at this point.

Is amblyopia preventable?
Early detection and treatment of amblyopia and significantly unequal refractive errors can help to reduce the chances of one eye becoming amblyopic.

How great a handicap is amblyopia?
Amblyopia is a handicap because it can limit the occupational and leisure activities you can do. Activities requiring good depth perception may be difficult or impossible to perform. In addition, should your good eye become injured or develop vision problems, you may have difficulty maintaining your normal activities.

This information was provided by the American Optometric Association (AOA). To find out more information visit their web site at www.aoanet.org/aoanet

What is farsightedness?
Farsightedness, or hyperopia, as it is medically termed, is a vision condition in which distant objects are usually seen clearly, but close ones are not brought into proper focus.

Why does farsightedness occur?
If the length of your eyeball is too short or the cornea has too little curvature, near objects cannot be brought into sharp and clearly focused images. Hereditary factors often control the growth and development of the eye. However, environmental factors may also contribute to the development of farsightedness.

How common is farsightedness?
Many people have some degree of farsightedness. The condition is only a problem if it significantly affects a person's ability to see. It is estimated that over half the people who wear glasses are wearing them because of a focusing problem due to farsightedness or presbyopia, a natural decrease in focusing ability at near distance.

What are signs/symptoms of farsightedness?
Common signs and symptoms of farsightedness include difficulty in concentrating and maintaining a clear focus on near objects, blurred vision, eye strain, fatigue and/or headaches after close work.

How is farsightedness diagnosed?
Farsightedness can be effectively diagnosed in a comprehensive optometric examination. Common vision screenings, often done in schools, are generally ineffective in detecting farsighted people. This is because these individuals can identify the letters on an eye chart with little difficulty.

How does farsightedness affect vision?
If you are farsighted, you involuntarily exert extra effort to maintain clear distance vision and even greater effort to see clearly at close range. This extra effort can cause fatigue, tension and discomfort. If the crystalline lens of the eye cannot bring the object being viewed into focus, blurred vision occurs.

How is farsightedness treated?
In mild cases, your eyes may be able to compensate adequately without the need for corrective lenses. In moderate or severe cases, your optometrist may recommend glasses or contact lenses.

How will farsightedness affect my lifestyle?
Most individuals adapt well to wearing glasses or contact lenses. After that, farsightedness will probably not significantly affect your lifestyle.

This information was provided by the American Optometric Association (AOA). To find out more information visit their web site at www.aoanet.org/aoanet

What is nearsightedness?
Nearsightedness, or myopia, as it is medically termed, is a vision condition, in which near objects are generally seen clearly, but distant objects are blurred and do not come into proper focus.

Why does nearsightedness occur?
When your eyeball is too long or the cornea has too much curvature, light entering the eye is not focused properly. Hereditary factors often control the growth and development of the eye. However, some evidence supports the theory that nearsightedness may also be caused by the stress of too much close vision work.

How common is nearsightedness?
Nearsightedness is a very common vision condition that affects nearly 30 percent of the American population. It normally first occurs in school age children. Since the eye continues to grow during childhood, nearsightedness generally develops before the individual reaches age 20.

How is nearsightedness diagnosed?
Nearsighted children are usually easy to identify because they often squint or have trouble seeing the chalkboard, the movie screen, the television set or other distant objects. A comprehensive optometric examination will include testing for nearsightedness.

How is nearsightedness treated?
Eyeglasses or contact lenses can be prescribed to optically correct nearsightedness and enable you to see more clearly. They alter the way the light images are focused in your eyes, but they do not cure nearsightedness. You may only need them for certain activities, like watching television, going to a movie or driving a car. In recent years, a number of options to surgically alter the shape of the cornea, the eye's clear front surface, to reduce nearsightedness have been developed. There is also a procedure called Corneal Refractive Therapy (CRT) or orthokeratology, which uses a series of rigid contact lenses to alter the curviture of the cornea to provide improved vision for extended periods of time. Your doctor of optometry can help you decide if these procedures are right for you.

How will nearsightedness affect my lifestyle?
Most individuals adapt well to wearing glasses or contact lenses. For those individuals who feel glasses affect their image or interfere with their activities, contact lenses, CRT or refractive surgery may provide options to better meet their lifestyle and vision needs. In some cases, more severely nearsighted individuals may find the condition limits their choice of occupations.

This information was provided by the American Optometric Association (AOA). To find out more information visit their web site at www.aoanet.org/aoanet

What is astigmatism?
Astigmatism is a vision condition in which light entering the eye is unable to be brought to a single focus, resulting in vision being blurred at all distances. Astigmatism is not a disease, but rather, a vision condition that is quite common. It often occurs in conjunction with other refractive errors like nearsightedness and farsightedness.

Why does astigmatism occur?
Typically, astigmatism is caused by the front of your eye (the cornea) being more oval than round, and not allowing light to focus properly on the back of your eye (retina). The causes of this irregular shape vary. In some cases, it may be hereditary or it may result from such factors as pressure of the eyelids on the cornea, incorrect posture or an increased use of the eyes for close work.

How common is astigmatism?
Most people have some degree of astigmatism. However, only individuals with moderate to highly astigmatic eyes usually need corrective lenses. What are the signs/symptoms of astigmatism? People with significant amounts of astigmatism will usually have blurred or distorted vision. Those with mild astigmatism may experience headaches, eye strain, fatigue or blurred vision at only certain distances.

How is astigmatism diagnosed?
A comprehensive eye examination by your doctor of optometry will include testing for astigmatism.

How is astigmatism treated?
Astigmatism can generally be optically corrected with properly prescribed and fitted eyeglasses or contact lenses. In recent years various ophthalmic laser surgical procedures, including LASIK, have been developed to alter the shape of the cornea to correct low or moderate astigmatism. There is also a procedure called Corneal Refractive Therapy (CRT) or orthokeratology, which uses a series of rigid contact lenses to provide improved vision for extended periods of time. Your doctor of optometry can help you decide if these procedures are right for you.

Does astigmatism get progressively worse?
Astigmatism may change slowly. Regular optometric care can, however, help to ensure that proper vision is maintained.

How will astigmatism affect my lifestyle?
You may have to adjust to wearing eyeglasses or contact lenses if you do not wear them now. Other than that, astigmatism probably will not significantly affect your lifestyle at all.

This information was provided by the American Optometric Association (AOA). To find out more information visit their web site at www.aoanet.org/aoanet

Presbyopia

What is presbyopia?
Presbyopia is a vision condition in which the crystalline lens of your eye loses its flexibility. This results in progressive difficulty in focusing on close objects.

What causes presbyopia?
Your eye stops growing in your early teens. The lens, however, continues to grow and produce more and more cells. This continued growth eventually causes the lens to harden and lose some of its elasticity and therefore some focusing ability.

At what age does presbyopia occur?
It varies from person to person. Although presbyopia may seem to develop suddenly, the actual decline takes place over the course of many years. Presbyopia usually becomes apparent to people in their early to mid-forties.

What are signs/symptoms of presbyopia?
Some signs/symptoms of presbyopia include the tendency to hold reading material at arm's length, blurred vision at normal reading distance and eye fatigue along with headaches when attempting to do close work.

Can presbyopia be prevented?
Unfortunately it cannot. Presbyopia is a natural part of the aging process.

How is presbyopia diagnosed?
A comprehensive eye examination by a doctor of optometry will include testing your near vision. This will determine the extent, if any, of presbyopia.

How is presbyopia treated?
To compensate for presbyopia, doctors of optometry prescribe reading glasses, bifocals, trifocals, progressive addition lenses or contact lenses. Since presbyopia can complicate other common vision conditions like nearsightedness, farsightedness and astigmatism, your optometrist will perform other tests to determine the specific lenses that will allow you to see clearly and comfortably for your daily visual needs. Your optometrist will also ask specific questions about your occupational and recreational activities. This information will aid in determining what type of lenses you need.

Will I have to wear glasses all the time?
This will depend on a number of factors, including any other vision conditions you have. You may only need your glasses for reading, working at your computer, sewing or other close work. However, you may find that wearing your glasses all the time is more beneficial and convenient for your vision needs.

Can I still wear contact lenses?
Great strides continue to be made in contact lenses. New technology is making it possible for doctors of optometry to correct many vision conditions, including presbyopia. You and your optometrist can decide whether contact lenses are right for you .

Why are frequent lens changes necessary after age 40?
The effects of presbyopia constantly change the ability of the eye's crystalline lens to focus properly. As a result, periodic changes in your eyeglasses or contact lenses are necessary to maintain good vision.

How will presbyopia affect my lifestyle?
After adjusting to your new eyewear, you should find that you can still do all the things you did before. Presbyopia will probably not have a significant effect on your lifestyle at all. You should, however, continue to have comprehensive optometric examinations as recommended by your doctor of optometry.

This information was provided by the American Optometric Association (AOA). To find out more information visit their web site at www.aoanet.org/aoanet

What is eye coordination?
Eye coordination is the ability of both eyes to work together as a team. Each of your eyes sees an ever so 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.

What causes poor eye coordination?
Eye coordination is a skill that must be developed. Poor eye coordination results from a lack of adequate vision development or improperly developed eye muscle control. Although rare, an injury, disease, tumor or other trauma can cause poor eye coordination.

How does poor eye coordination affect vision?
Since 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 on the muscles to maintain proper alignment of the eyes. In more severe cases, the muscle cannot adjust the eyes so that the same image is seen and double vision occurs. Since 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.

What are signs/symptoms of poor eye coordination?
Some signs/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 the place while reading, poor sports performance, avoiding tasks that require close work and tiring easily.

How is poor eye coordination diagnosed?
Since poor eye coordination can be difficult to detect, periodic optometric examinations beginning at age 3 are recommended. A comprehensive examination by a doctor of optometry will determine the extent, if any, of poor eye coordination.

How is poor eye coordination treated?
Poor eye coordination is often successfully treated through vision therapy, contact lenses and/or other optical aids. If detected early enough, the success rate for achieving proper eye coordination is quite high. In some cases, eye coordination will improve when other vision conditions like nearsightedness or farsightedness are corrected. In some cases, surgery may be necessary.

This information was provided by the American Optometric Association (AOA). To find out more information visit their web site at www.aoanet.org/aoanet