Monocular treatment for amblyopia, such as patching or penalization, does not always result in 20/20 vision. Moreover, recurrence of amblyopia is not uncommon after these monocular forms of treatment. Classically, amblyopia has been thought to be due to passive suppression of the amblyopic eye, due to a passive reduction of excitation of the binocular system. Hence, the classic form of monocular treatment of amblyopia focuses on improving vision of the amblyopic eye with the expectation that improved vision in the amblyopic eye will lead to improved binocular vision.
However, it has been suggested that monocular treatment actually does the opposite–it slows down the process of developing and even impairs binocular function. Furthermore, recent studies suggest amblyopia is actually due to an active process. The loss of binocular vision in strabismic animal models was shown to be reversible when a pharmaceutical agent (GABA antagonist) was used to remove the inhibition, which indicates amblyopia is due to active suppression. In addition, a meta-analysis study (the highest form of clinical research) in 2022[1], illustrated that binocular treatment of amblyopia improves visual acuity, depth perception, and binocular function and suggests binocular vision therapy is an effective treatment for amblyopia. In contrast to classical monocular forms of therapy, binocular forms of vision therapy aims to minimize suppression of the amblyopic eye and thus improving not only the vision of the amblyopic eye, but also simultaneously, binocular function.
Recent research such as these has sparked a primary focus on binocular treatment for amblyopia in clinical practice. Another research study[2] investigated a binocular form of treatment for amblyopia utilizing an iPad where children wearing anaglyphic glasses played binocular games versus monocular games. This study illustrated that binocular treatment of amblyopia rapidly improved visual acuity, and visual acuity was stable for at least 3 months following completion of treatment. However, one limitation of this study was that it was a small-scale study with limited eligible children. Although research recently has started to solidify binocular treatment of amblyopia as an effective form of treatment, further research is still yet to be conducted to determine the extent of efficacy, effectiveness, and longevity of binocular treatment of amblyopia and the comparison between binocular treatment as a stand-alone therapy versus binocular in conjunction with monocular forms of treatment.
References 1. Jin, L., Fang, Y., & Jin, C. (2022). Binocular treatment for individual with amblyopia: A systematic review and meta-analysis. Medicine, 101(27).
2. Birch, E. E., Li, S. L., Jost, R. M., Morale, S. E., De La Cruz, A., Stager Jr, D., ... & Stager Sr, D. R. (2015). Binocular iPad treatment for amblyopia in preschool children. Journal of American Association for Pediatric Ophthalmology and Strabismus, 19(1), 6-11.
Steven Kim
Optometry Extern Chicago Collage of Optometry
and Midwestern University