Function Influencing Structure in Amblyopia

It’s the ultimate example of neuroplasticity: the ability of amblyopia therapy to improve the retinal microvasculature in the vicinity surrounding the foveal avascular zone. A new study published in JAAPOS shared with us from Dr. Curt Baxstrom, who was alerted to it by Dr. John Tassinari, supports this concept.

From the article, here was the treatment protocol: “Treatment spanned 6 months. For the first 3 months, mild amblyopic subjects underwent optical correction, moderate amblyopic subjects completed optical correction and 2 hours of daily patching, and severe amblyopic subjects completed optical correction with 6 hours of daily patching. After 3 months of treatment, we remeasured all patients’ refraction without cycloplegia and visual acuity. Based on the improvement that each patient experienced at this timepoint, we adjusted our treatment protocol for the next 3 months of treatment. For patients whose amblyopic eye visual acuity improved significantly (ie, ≥1 line of improvement), treatment remained unchanged. However, for those who experienced little or no improvement in their amblyopic eye visual acuity, we increased daily patching by 2 hours.”

It matters much less that the treatment approach here involved patching, absent any of the more contemporary optometric approaches to therapy. The important point is that results suggest the existence of retinal microstructural deficits in unilateral amblyopia, with the foveal avascular (FAZ) shape more irregular in amblyopic eyes. Above all, FAZ shape became more regular after amblyopia treatment, along with improved best-corrected visual acuity (BCVA) in the amblyopic eyes.

 Foveal avascular zone (FAZ) circularity changes after 6 months of amblyopia treatment. FAZ circularity at baseline (before treatment) in amblyopic eyes (A) and in the fellow eyes (B). After optical correction and patching therapy for 6 months, FAZ circularity in amblyopic eyes increased to (C), and fellow eyes remained stable.

Take a look at our original post about structure vs. function in amblyopia in 2012, and at the follow-up post on structure vs. function in amblyopia in 2018.

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