Amblyopia is a condition where the vision is reduced in the eye because the eye and the brain are not working together properly.
The eye needs to have a clear image projected onto the retina and both eyes need to be fully aligned for the brain to be able to develop vision properly out of each eye. The retina is the light sensitive layer of light receptors that gather visual information and then send it to the brain via the optic nerve. If the image is blurred on the retina on one eye, but not the other due to a difference in prescription of each eye, the brain may choose to develop more connections with the eye that sees more clearly. This would lead to the eye with a larger prescription developing Amblyopia.
The prescription can be due to Hyperopia, Myopia and or Astigmatism. Another reason for Amblyopia to develop is if one eye is turned in or out. Imagine the brain has the choice of viewing through the two eyeballs, like if you had two video cameras to look through. If both cameras point to the same objects together then the brain can do a special trick called ‘fusion’, which allows for the picture to look slightly larger, more comfortable and allow 3D viewing. If one of the eyes, or cameras in this example, point at a different angle to the other, the brain has either the choice of looking at double vision or turning off the image of the turned eye (suppression). This suppression is an adaptation of the brain to try and avoid double vision when the eyes can’t co-ordinate together properly. Unfortunately, though this leads to Amblyopia.
Another example where the eyes can become Amblyopic is if the image of light is obscured by a droopy eyelid or cataract. Thus, light does not fall properly on the retina to stimulate the connections between the eye and the brain and one or both eyes can become Amblyopic.
The first line of treatment involves prescribing glasses, giving good vision to that eye usually solves the problem. Sometimes further treatment such as patching or blurring of the “good” eye is necessary to try and force the weaker eye to improve its vision.