What is Anisometropia?
In normal vision the image that falls on the retina, at the back of the eye is the same size and shape, or very nearly so. The term used to describe the vision that is perceived through both eyes together is Binocular Vision. In good Binocular Vision the difference between the size of the images in each eye is less than 0.5%, however people with poor binocular vision can have a difference of up to 20%. The Human Visual system can cope with a difference of about 5%.
Anisometropia, is a congenital condition in which the above condition occurs, because the two eyes have unequal total refractions. To put it in simple terms, one eye sees a much larger image than the other eye, resulting in a blurred image. In the condition Aphakia, when one of the eyes has had it's lens surgically removed, and an IOL (Intra Ocular Implant), placed within the eye (usually as the result of Cataract Surgery), similar symptoms can occur, because the implanted lens will be designed to give the best vision possible for the patient, while the other eye remains unchanged.
If this condition is present in infancy and is undetected or untreated, it often results in the development of lazy eye or amblyopia in the more hyperopic (far-sighted) eye. The greater the amount of the difference, the more likely the development of lazy eye will be.
Can Anisometropia be treated?
Yes,Anisometropia can usually be corrected with spectacles, however, in cases where the patient has had this condition for a long period of time, it is difficult for them to simply put on a pair of spectacles and see more clearly. In severe cases, the weakest eye will often be ignored by the brain, and although the eye is capable of seeing, the brain will choose the strongest eyes . So when spectacles are applied to the patient, the brain has to "learn" to use the eye again, and this can take some time.
How is Anisometropia treated?
In most Cases, treating Anisometropia, is just a matter of finding a prescription to correct help correct the problem, but it also has to be a prescription that the patient feels comfortable with, and can adapt to relatively quickly. The full prescription may not be given straight away, but may be increased over a period of time