Subfoveal choroidal thickness in relation to sex and axial length in 93 Danish university students.

PURPOSE To investigate the association between subfoveal choroidal thickness and ocular axial length, refractive error, and blood pressure in healthy young women and men. METHODS Cross-sectional observational study of 93 eyes in 93 healthy Danish university students (mean age 24.9 ± 2.6 years). The submacular choroid was imaged using enhanced-depth imaging spectral domain optical coherence tomography. Subfoveal choroidal thickness was measured by visual inspection and manual fitting of the choroidal borderlines. Study parameters included history, best corrected visual acuity, objective refraction, interferometric ocular axial length, fundus photography, and blood pressure manometry. RESULTS The mean subfoveal choroidal thickness was 342 (±118) μm, the mean age was 24.9 (±2.6) years and the mean refractive error of participants was -1.43 (±2.9) diopters (D). In a multiple regression model, subfoveal choroidal thickness decreased by 58.2 μm (95% confidence interval [CI], 42.2-74.2 μm; P < 0.001) per mm increase in axial length adjusted for age and sex and subfoveal choroidal thickness was 62 μm (95% CI, 21-104 μm; P = 0.0039) thicker in men than in women, adjusted for age and axial length. Arterial blood pressure had no statistical effect on subfoveal choroidal thickness. CONCLUSIONS In this study of healthy young participants choroidal thickness was 18% higher in men than in women when adjusting for age and axial length. This observation may help explain the effect of sex in conditions related to choroidal thickness such as myopia, central serous chorioretinopathy, and age-related macular degeneration.