To examine predictive factors for visual acuity in highly myopic eyes.
Consecutive patients with high myopia (≥6 diopters [D]) with no other pathology such as lacquer cracks in the fovea, choroidal neovascularization, or myopic macular schisis, were evaluated. The study was performed in 2 retina centers, one in the United States and the other in Japan. Enhanced depth imaging optical coherence tomography was obtained, and the central foveal, outer retinal hyporeflective layer and inner segment to retinal pigment epithelium aggregate, and the subfoveal choroidal thicknesses were measured. Correlations were calculated among the measured variables and visual acuity. Generalized estimating equation models were used to identify predictors of visual acuity.
The New York cohort was composed of 35 eyes of 25 patients who had a mean age of 57 years (standard deviation, ±18.1 years) and a mean refractive error of −10.9 D (±3.6 D). The Japanese cohort was composed of 110 eyes of 61 patients who had a mean age of 46.8 years (±14.7 years) and a mean refractive error of −9.2 D (±3.1 D) and a mean axial length of 27 mm (±1.4 mm). The mean subfoveal choroidal thickness was 113.3 μm (±53.9 μm) in the New York group and 172.9 μm (±72.8 μm) in the Japanese group. In each group, the subfoveal choroidal thickness showed a significant inverse correlation with age and myopic refractive spherical equivalent. The subfoveal choroidal thickness was inversely correlated with logarithm of the minimum angle of resolution visual acuity (P = 0.041, New York group; P = 0.001, Japan group). The only significant predictor in the pooled data for logarithm of the minimum angle of resolution visual acuity was subfoveal choroidal thickness (P ≤ 0.001). Clinic location was not a significant predictor.
Choroidal thickness in high myopia is inversely correlated with increasing age and myopic refractive error and is an important predictor of visual acuity. Given that myopia is increasing worldwide, these findings may have epidemiologic significance.