Amblyopia is the inability of one or both eyes to be corrected to 20/20 with conventional means (glasses, contact lenses, refractive surgery). At birth only approximately one third of the nerve fibres of the optic nerve are connected to the visual cortex in the brain. The remaining two thirds of the fibres develop their connections up until around age 7. If something interferes with this development then amblyopia will onset. The two most common causes of amblyopia are strabismic and refractive. In strabismic amblyopia one of the eyes is turned. This may be turned inwards, outwards or up or down. As a result of this eye turn the turned eye does not receive a clear image on the fovea and the optic nerve fibres fail to develop their connections in the turned eye resulting in the decreased acuity. In refractive amblyopia, one of the eyes has a significantly higher prescription than the other and this goes undetected and thus uncorrected with glasses. The eye with the higher prescription never sees clearly and this results in the development of amblyopia. Amblyopia is present in about 4% of the population.
Fortunately, amblyopia is completely preventable if diagnosed and treated early on. This is why we recommend the first eye exam in a child’s life be at age 6 months. New research has shown that amblyopia is NOT a problem with one of the eyes (the turned eye or the eye with the higher prescription). Amblyopia is in fact a binocular problem – the two eyes are unable to work together simultaneously to provide normal vision. Previously the gold standard treatment was penalization therapy – patching the good eye to force the the “lazy eye” to work. This worked in some cases with some degree of success, but in many cases failed. Now that we know amblyopia is a binocular problem, therapy for amblyopia now is targeted at developing the ability to help the two eyes work together. Vision therapy for amblyopia is most effective and the speed of success is much more rapid before the age of 7; however, amblyopia can be treated at any age. If you have amblyopia, book your assessment today.