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  • Using OCTA to Assess Amblyopia

    By Lynda Seminara
    Selected and Reviewed By: Neil M. Bressler, MD, and Deputy Editors
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    Journal Highlights

    JAMA Ophthalmology, August 2020

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    The diagnosis of amblyopia is estab­lished by exclusion, and little is known about the retinal microvasculature of this condition. Although high-reso­lution imaging has shed some light on microvascular issues, the clinical significance of the findings is unclear. Wong et al. studied quantitative metrics of optical coherence tomography angiography (OCTA) in eyes with and without amblyopia to explore potential relationships with visual acuity (VA). They found that amblyopic eyes had abnormal macular microvasculature, including decreased foveal avascular zone (FAZ) circularity, lower fractal dimension, and greater vessel diame­ter index. The metrics associated with VA in their study were avascular zone circularity and vessel diameter index.

    For this study, the authors recruited children between the ages of 6 and 8 from the population-based Hong Kong Children Eye Study. They defined am­blyopia as best-corrected VA between 20/40 and 20/200 in one or both eyes, with no identifiable organic cause for the decreased vision.

    Only eyes with strabismic or anisometropic amblyopia were included. For patients with bilateral amblyopia, the eye with poorer vision was used. Children with BCVA of 20/20 or better were included in the control group if a full ophthalmic exam showed no evi­dence of any ocular abnormality; only their right eyes were analyzed.

    All participants underwent swept-source OCTA and detailed exams. Mac­ular microvasculature of the superficial capillary plexus was quantified by a customized automated image-analysis program. Differences in OCTA metrics between amblyopic and control eyes were analyzed by multivariable linear regression, with adjustments for all known confounders. The metrics assessed were fractal dimension, FAZ area and circularity, vessel density, and vessel diameter index.

    The analysis set included 30 children with amblyopia and 1,045 controls. Compared with control eyes, those with amblyopia showed decreased FAZ cir­cularity (−0.058; p = .002), lower frac­tal dimension (−0.014; p = .01), and higher vessel diameter index (0.002; p < .001). There was no meaningful difference in FAZ area or vessel density. LogMAR visual acuity was associated with FAZ circularity (sβ, −0.133; p < .001) and vessel diameter index (sβ, 0.097; p = .001) but not with FAZ area or vessel density.

    The findings suggest that children with amblyopia have morphologic anomalies in macular microvascula­ture; such changes are linked to poorer VA. The authors believe that OCTA and specific OCTA metrics have the poten­tial to be reliable, objective, automated tools for recognizing amblyopia. (Also see related commentary by Tock H. Lim, MBBS, MMed, and Colin S. Tan, MBBS, MMed, in the same issue.)

    The original article can be found here.