Purpose:
To evaluate choroidal thickness at different distance from the fovea in normal eyes, normal myopic eyes, and myopic eyes with choroidal neovascularization (CNV).
Methods:
Volunteer subjects were enrolled in the study with informed consent and divided into 4 groups: 3 normal groups (normal, myopic, and highly myopic) with different levels of refractive error and a 4th group of highly myopic eyes with CNV. Horizontal B-scan images through the fovea center were acquired with RTVue (Optovue, Fremont, CA), a FD-OCT device. Choroidal thickness was obtained from fovea center, 200µm, 400µm, 500µm,1000µm, and 1500µm away from the fovea center for all study eyes with sufficiently clear choroid-sclera boundary.
Results:
There are a total of 82 eyes enrolled in the study, of which 58 eyes (71%) yielded sufficient contrast for delineating the choroid-sclera boundary. The mean choroidal thickness and standard deviation directly under the center of the fovea are 321.0±78.7 (µm) for the normal group (n=23), 231.4±44.7 (µm) for the myopia group (n=7), 89.2±60.6 (µm) for the high myopia group (n=19), and 105.3±67.3 (µm) for the high myopia with CNV group (n=9). There is an obvious and similar amount of reduction in choroidal thickness associated with myopia in all the locations evaluated. The choroidal thickness appears slightly thicker at the fovea center as shown in the plot.
Conclusions:
Choroidal thickness can be easily measured using FD-OCT scans in normal and myopic eyes. Choroidal thickness across the macula shows a thicker choroid at fovea level, thinner nasally and temporally and a tendency to decrease with higher myopia.
Keywords: choroid • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • myopia