Amblyopia

Amblyopia is defined as lowered visual acuity without obvious cause. It is a condition where the brain switches off one eye because there is conflicting or unequal input from the two eyes. Recently Ambliopia is also thought of as a sensory adaptation to Strabismus a condition where one eye is looking in a different direction. Amblyopia is a label that is often applied to a wide range of visual conditions where there is a diffrence between the eyes. Technically if both eyes have visual imput then the condition is anisometropia - a difference in visual acuity between the eyes. This is the case for many people.

Amblyopia may develop due to a number of reasons such as: Deviating eye Amblyopia is likely to develop in children under the age of 3 if one eye is deviating (turning in or out) as in strabismus. If untreated marked decrease in visual acuity may develop within just a few weeks.

Defocused eye

When one eye is severely near-sighted and the images appear blurred at all distances amblyopia is likely to develop. In adults having one eye that is severely near-sighted though wearing corrective lenses may develop amblyopia if vision training is not commenced. There simply is a slow deterioration as you get progressively stronger and stronger lenses.

Deprived eye

Amblyopia can develop as a result of covering one eyes for the whole day for as little as a week during the early stages of an infants vision development. The medical treatment of choice is patching the good eye, which over the years have been supplemented with active stimulation of the eye using electrical and chemical stimulants. Strategies used are total occlusion, excluding all light. For example using adhesive patches worn on the skin. Opaque black contact lenses, frosted glass and other filters may be used. Total occlusion is considered more effective than part time covering of the good eye.

Amblyopia is treated in childhood and is rarely started after age eight. The rule of thumb is to occlude the good eye for as many weeks as the child is old. If Strabismus is involved there is often surgical replacement of the eye muscles in an attempt to straighten the eye so both eyes are moving together for better cosmetic appearance. In a study, conducted by Watson et al. in 1985, comparing the effects of full time and part time occlusion reported that 23% of the patients showed no improvement despite very adequate and vigorous treatment. I have talked to many people who have gone though this treatment in childhood.

They all told me that they hated wearing the patch and that it didn't’t make much difference anyway. This is not to say that eye-patches do not work. They do, but the success rate is depressingly low. If you are a parent you can imagine how impossible it is to keep a eye-patch on a 4 year old child. In some cases the child’s arms have been put in splints to prevent them from ripping the patch off. Today many people would consider such measures child abuse.

The problem with the above approach is that it is passive and does not involve the mind. You are in essence trying the force the eyes to function normally. Amblyopia should be treated as soon as it is detected. However, in many cases people do not realize that they are using only one eye to see. It is a very gradual shift that is barely noticeable. Unfortunately there is a large number of adults with untreated amblyopia.