Visual acuity and subfoveal choroidal thickness: the Beijing Eye Study.

Purpose: To examine the association between best corrected visual acuity (BCVA) and subfoveal choroidal thickness.

Design: Population-based study.

Methods: The Beijing Eye Study 2011 included 3468 subjects with ages of 50+ years. The participants underwent an ophthalmologic examination including spectral-domain optical coherence tomography with enhanced depth imaging for measurement of choroidal thickness. BCVA was measured as logarithm of the minimal angle of resolution.

Results: Of the 3468 participants, choroidal measurements were available for 3233 (93.2%) subjects. In multivariate analysis, better BCVA was significantly associated with thicker subfoveal choroid (P < 0.001) in general and a subfoveal choroid thicker than 30 μm (P < 0.001) in particular, after adjusting for younger age (P < 0.001), higher level of education (P < 0.001), taller body stature (P < 0.001), higher body mass index (P = 0.005), absence of glaucoma (P = 0.001), absence of diabetic retinopathy (P < 0.001), absence of late-stage age-related macular degeneration (P < 0.001), and axial length shorter than 26.0 mm (P < 0.001) (correlation coefficient r:0.56). If eyes with glaucoma, diabetic retinopathy, late-stage age-related macular degeneration or myopic retinopathy were excluded, better BCVA was still significantly associated with thicker subfoveal choroid (P < 0.001) and subfoveal choroid thicker than 30 μm (P < 0.001) in multivariate analysis. In a reverse manner, thicker subfoveal choroid was associated with better BCVA (P < 0.001) after adjusting for younger age (P < 0.001), male gender (P < 0.001), longer axial length (P < 0.001), and higher corneal curvature radius (P < 0.001).

Conclusions: Better visual acuity is strongly associated with thicker subfoveal choroid independent of additional factors, such as age, axial length, education level, and major ocular diseases.