Choroidal Thickness and Volume in Healthy Young White Adults and the Relationships between them and Axial Length, Ammetropy and Sex

Abstract

To evaluate choroidal thickness in young adults using enhanced-depth imaging spectral-domain optical coherence tomography and to describe volume differences in all the areas defined in the Early Treatment Diabetic Retinopathy Study. Prospective clinical study. In 95 healthy young (23.8 ± 3.2 years) adult volunteers, 95 eyes were prospectively enrolled. Manual choroidal segmentation on a 25-raster horizontal scan protocol was performed. The measurements of the 9 subfields defined by the Early Treatment Diabetic Retinopathy Study were evaluated. Mean subfoveal choroidal thickness was 345.67 ± 81.80 μm and mean total choroidal volume was 8.99 ± 1.88 mm(3). Choroidal thickness and volume were higher in the superior and temporal areas than in the inferior and nasal sectors of the same diameter, respectively. Strong correlations between subfoveal choroidal thickness and axial length and myopic refractive error were obtained (r = -0.649, P < 0.001, and r = 0.473, P < 0.001, respectively). Emmetropic eyes tended to have thicker subfoveal choroidal thickness (381.94 ± 79.88 μm vs 307.04 ± 64.91 μm) and higher total choroidal volume than myopic eyes (9.80 ± 1.87 mm(3) vs 8.14 ± 1.48 mm(3)). The estimation of the variation in the subfoveal choroidal thickness in relationship to the axial length was -43.84 μm/mm. In the myopic group, the variation in the subfoveal choroidal thickness with the myopic refractive error was -10.45 μm per diopter. This study establishes for the first time a normal database for choroidal thickness and volume in young adults. Axial length, and myopic ammetropy are highly associated with choroidal parameters in healthy subjects. Enhanced-depth imaging spectral-domain optical coherence tomography exhibited a high degree of intraobserver and interobserver repeatability.