Amblyopia, commonly known as a “lazy eye,” is when there is reduced visual acuity in one or both eyes. The patient often suppresses (ignores) the visual information coming from the amblyopic eye. Regardless of the type of amblyopia, I start my patient monocularly to have the patient gain awareness of both eyes separately and equalize their performance in localizing an object. Once the patients are used to using one eye at a time, I have the patient do biocular activities to allow the patient to gain an understanding and awareness of when the eye is on or off. We enter binocular activities after the patient gains control and consistently uses both eyes. While progressing through the various stages of binocularity, we continue to work on eye control, accommodation, and localization in unison with these activities.
I often use superimposition, a biocular activity where the patient puts a mirror on their nose at a 45-degree angle where one eye is looking through the mirror and the other is looking at a target. This activity is done in a corner of a room where I can put one image on one wall and one image on the other wall so that they can overlap. The patient aims to see both images come together during this activity. In my sessions, I use either two pieces of colored paper or a butterfly and a circle. I start the activity by having the patient focus on either the butterfly or the circle and see primarily just that object while the other eye is open, and then switch to the other object and see primarily that object. Once the patient gains awareness of each eye, I have the patients see both images together. Various targets can help the patient gain the awareness necessary to succeed with the activity.
Refractive amblyopia results from a difference in asymmetric uncorrected refractive error (high nearsightedness, farsightedness, or astigmatism) between the two eyes. This prevents a clear image from stimulating the fovea, causing the brain to favor the eye with better vision. This often results in suppression in the amblyopic eye.
Strabismic Amblyopia is caused by the eye’s axis being misaligned in any direction (inward, outward, upward, or downward) compared to the other eye. The misalignment causes the brain to not have the opportunity to learn how to fuse the images between the eyes together and causes the brain to ignore the mismatched image from the deviated eye.
When treating Strabismic Amblyopia, it might take a bit longer to get binocular vision due to having multiple visual deficits. My vision therapy programs differ as I spend more time working on proprioceptive activities for someone who has Strabismic amblyopia so that the patient can understand where the eye is pointing. Whereas with Refractive Amblyopia, I would spend more time working on accommodative-based activities to allow the patient to build awareness around adjusting their accommodative system.
When doing binocular activities with amblyopic patients, I still want the patient to be aware of when they are suppressing. This can be done with red and green glasses with activities such as Binocular Accommodative Rock (BAR), GTVT Hart chart, or Anti-suppression cards. Activities such as free space fusion cards also allow the patient to recognize whether they are using their eyes together without red and green glasses. I find Tranaglyphs and Vectograms to be helpful tools because to see the three-dimensional picture, the patient will have to team their eyes together in a certain spot in space. If the patient suppresses, the image will not look like it is popping out or going in. It will look two-dimensional. The two cards can either make the patient converge or diverge (based on what the patient needs the most help with), which can be made harder or easier based on how far apart I slide the images.
Treatment for Amblyopia is an extensive process and requires active participation. I give home support activities for the patient to do outside of when they have their session to aid the process. Treating Amblyopia early typically allows the patient to progress quicker through their vision therapy program and has less of an impact in later developmental stages. Treating adults requires more time, practice, and patience as they have compensated for the lack of acuity in one eye for a longer period of time. Doing activities that allow for visual feedback is crucial for amblyopic patients. Getting feedback from the patient also allows me to adjust the program to make the program either harder, easier or to take a completely different approach.
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