Association of Optical Coherence Tomography Angiography Metrics with Detection of Impaired Macular Microvasculature and Decreased Vision in Amblyopic Eyes: The Hong Kong Children Eye Study

Abstract

Importance: Microvascular abnormalities in amblyopia are becoming evident with high-resolution imaging, such as optical coherence tomography angiography (OCT-A); however, to our knowledge, the clinical significance and use of these findings are unknown. Objective: To assess changes in quantitative OCT-A metrics in amblyopic eyes and explore their association with visual acuity in children. Design, Setting, and Participants: This population-based nested case-control study included children aged 6 to 8 years who were consecutively recruited between January 2016 and July 2017 from the population-based Hong Kong Children Eye Study (HKCES) at the Chinese University of Hong Kong Eye Centre. All participants underwent OCT-A with a swept-source OCT and detailed ophthalmic investigations. Macular microvasculature of the superficial capillary plexus was quantified by a customized automated image analysis program. A multivariable linear regression was conducted to evaluate the differences in OCT-A metrics between amblyopic and nonamblyopic eyes after adjustment for all known confounders. Data analysis was conducted from September to November 2018. Main Outcomes and Measures: Differences in OCT-A metric (foveal avascular zone [FAZ]) area, FAZ circularity, vessel density, vessel diameter index, and fractal dimension between amblyopic and nonamblyopic eyes. Results: There were 30 participants with amblyopia (mean [SD] age, 7.57 [1.2] years; 16 girls [53.3%]) and 1045 controls (mean [SD] age, 7.65 [1.0] years; 580 girls [55.5%]) in this cohort. Compared with control eyes, amblyopic eyes had decreased FAZ circularity (-0.058; 95% CI, -0.096 to -0.021, P =.002), decreased fractal dimension (-0.014; 95% CI, -0.024 to -0.003; P =.01), and increased vessel diameter index (0.002; 95% CI, 0.002 to 0.003; P <.001). A difference was not identified between FAZ area and vessel density. LogMAR visual acuity was associated with FAZ circularity (sß, -0.133; P <.001) and vessel diameter index (sß, 0.097; P =.001) but not with vessel density nor FAZ area. Conclusions and Relevance: The results of this population-based study in children supports the presence of macular microvascular abnormalities in amblyopic eyes. Such changes as measured by OCT-A metrics are associated with visual acuity, inferring retinal involvement in the development of amblyopia and suggesting a potential role of quantitative OCT-A metrics in the diagnosis and recognition of amblyopia.