As eye care professionals, at some point you have had a patient with amblyopia. Traditionally amblyopia was thought to be a problem with one eye (monocular), and the person with the condition didn’t have the binocular cell cooperation in his or her brain. Conventional treatments took a monocular approach, which included covering the good eye in order to create neural connections from the amblyopic eye to the brain. The thinking behind this type of treatment was that amblyopia needs to be treated before age 12, or else the child will have compromised vision for the rest of his or her life.
Not so fast. Research is showing that more can be done to improve the outcomes of those with amblyopia. Mere patching the “good eye” isn’t quite as good.
Scientists out of Vanderbilt University have learned that visual signals are merged as they arrive in the neocortex, so that even though we have two eyes are that taking in visual information, we see one image. Earlier it was thought that visual information was merged at a later stage of brain processing. Knowing which neurons are involved with visual processing can lead to targeted brain therapies to treat amblyopia.
“There are six functionally distinct layers in the primary visual cortex,” said Vanderbilt Ph.D. student Kacie Dougherty, who is working with the study’s author Alexander Maier, assistant professor of psychology at the university. “We thought the initial processing happened in the upper layers, but it’s actually in the middle. That’s vital information for developing treatments.”
Wait, there’s more amblyopia news! Not only is the visual system more flexible than previously thought, this flexibility means that people who are well into adulthood can be successfully treated. Researchers at McGill University in Montreal, Canada have developed a binocular treatment that has been shown to improve vision in those with amblyopia.
What the researchers at McGill did was to create a treatment that prevented one eye from suppressing the other. The definition of amblyopia is the suppression of the amblyopic eye input that results in the visual system behaving as if it is monocular. That means amblyopia can corrected by way of anti-suppression techniques, which help to overcome the functional defect in the affected eye.
The goal of the McGill University treatment is to create a viewing experience that prevents one eye from suppressing the other. This allows visual information from each eye to combine normally. After undergoing this treatment, there is a strengthening of binocular vision and a combination of binocular information under normal viewing conditions. In addition, there is a development of three-dimensional depth perception. Active optometric vision therapy can improve visual performance in the areas that are deficient in a person with amblyopia, such as fixation, spatial perception, and binocular function.
While this treatment has been successful, there is no guarantee that amblyopia won’t come back, so it is important that there are follow up appointments scheduled after treatment in order to monitor a patient’s progress.