Choroid Thickness Measurement with RTVue Optical Coherence Tomography in Emmetropic Eyes, Mildly Myopic Eyes, and Highly Myopic Eyes

Abstract

Purpose. To evaluate choroid thickness (CT) with RTVue spectral domain optical coherence tomography (SD-OCT) and the effect of age and myopia in eyes without posterior complications. Methods. In this multicenter cross-sectional study, all enrolled patients were over age 18 and divided them in 3 groups based on refraction: emmetropia (+1 D to −1 D), mild myopia (–1 D to −6 D), and high myopia (–6 D to −20 D) groups. Horizontal scans through the fovea were acquired with RTVue OCT (Optovue Inc., Fremont, California, USA). Choroid thickness was measured at 500 µm intervals up to 1,500 µm temporal and nasal to the fovea by 2 graders. Mean CT was calculated based on the average of the 7 locations. Statistical analysis was performed to evaluate CT at each location, the effects of age and myopia, and grader agreement. Results. A total 85 eyes of 85 subjects (30 emmetropic, 24 myopic, and 31 high myopic) were enrolled. Excellent grader agreement was observed with an intraclass correlation coefficient (ICC) >0.97. The mean CT was 248.2±78.5 (µm) for emmetropia (age = 58±18), 247.0±85.4 (µm) for myopia (age = 45±20), and 131.5±70.9 (µm) for high myopia (age = 54±13). The mean CT was not significantly different between emmetropia and myopia groups, which were significantly thicker than high myopia group. The overall slope of age-related change for the mean CT was −1.95 µm/y and the effect of age differed among the groups. Conclusions. Choroid thickness can be measured from RTVue OCT images with good reproducibility. Age and high myopia appear to negatively affect CT. The age effect may vary with refraction groups.