Amblyopia, commonly known as a “lazy eye,” 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, the patient will start monocularly to 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, they will do biocular activities to gain an understanding and awareness of when the eye is on or off. After they gain control and consistency using both eyes, we move into binocular activities. While progressing through the various stages of binocularity, we continue to work on eye control, accommodation, and localization in unison with these activities.
Superimposition is a biocular activity in which 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 the corner of a room where one image is on one wall and one image on the other wall so they can overlap. When doing this activity, the patient’s goal is to see both images come together. Pictures such as a a butterfly and a circle can complete this activity. First, have 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 prevents the brain from learning how to fuse the images between the eyes and causes it 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. Vision therapy programs may differ as more time should be spent working on proprioceptive activities for someone who has Strabismic amblyopia so that the patient can understand where the eye is pointing. Meanwhile, with Refractive Amblyopia, more time should be spent working on accommodative-based activities to allow the patient to build awareness of adjusting their accommodative system.
When doing binocular activities with amblyopic patients, the goal is to help them 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 realize if they are using their eyes together or not without red and green glasses. Tranaglyphs and Vectograms are helpful tools because in order 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. Home support activities are given 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 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 longer. Doing activities that allow for visual feedback is crucial for amblyopic patients. Getting feedback from the patient also allows the therapist to adjust the program to make it either harder or easier or to take a completely different approach.
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