In amblyopia the loss of vision is due to the lack of development of the connections between the eye and the brain. Therefore, by definition, a child with amblyopia has healthy eyes, yet the brain cannot see.
The cause of amblyopia is when there is interference in the infant’s binocular (2- eyed) visual development. This means that amblyopia occurs when the visual brain of the baby stops developing normally from the lack of proper “two-eyed” visual input. As a result, even with healthy eye structure, the child is not able to see clearly from the affected eye. This is with and without glasses. So, a child with amblyopia will typically have normal eye sight in one eye and the other eye will at least 2 lines worse. In addition to poor sight, the child with amblyopia will also have poor depth perception and other visual skills, like clarity of focusing and smooth eye movement. Amblyopia can be causes by an eye that turns or an eye that has a significant difference in the prescription compared to the other eye.
Occlusion therapy or “patching” is where the patient wears an eye patch on the “good eye” for a set number of hours during the day. While the research shows that a child’s visual brain will show improvement in their amblyopic eye sight with a patching regimen, this traditional approach (when used alone) can be very difficult and disruptive for the developing child to handle. It creates visual disorientation and confusion in spatial judgements. This creates frustration and often emotional upset in the patient. Furthermore, unilateral patching therapy only teaches a patient how to be a “one eyed person” since it does not address the underlying cause for the amblyopia which is the lack of binocular (two-eyed) vision development.
Therefore today’s best practices approach for the treatment of amblyopia involves a combination of monocular and binocular training of the visual brain through office-based vision therapy. This type of treatment aids the brain to “turn on” the poorer seeing eye channel and put it together with the other eye’s visual input. This restores 3-D vision. Vision therapy also addresses the other visual skills, like eye movements and focusing skills, creating a comfortable visual system with efficient functioning. Today, we now know that vision therapy can improve the depth perception of any patient, with no limitations on age.