Purpose:
High-penetration optical coherence tomography (HP-OCT) enables to visualize the deep choroidal structures. This study was conducted to measure the choroid and scleral thickness and establish the normalized database in normal Japanese subjects.
Methods:
A custom-built HP-OCT (Swept source, 50,000 A-scan/s, 1060 nm wavelength) was used to image 141 eyes of 125 subjects with no ophthalmologic symptom. The scan protocol was 6 x 6 mm square containing 512 x 256 A-scans. Retinal thickness was measured at the fovea. Choroidal thickness was measured at the fovea, 3mm superiorly, inferiorly, temporally, and nasally. Eyes with macular complications or any ophthalmological history were excluded. Chorio-scleral interface was clearly visualized in all eyes. Full thickness sclera was clearly visualized in 17 eyes, in which scleral thickness was available (Figure). Association of subfoveal choroidal thickness with other parameters was analyzed.
Results:
Average retinal thickness was 231 microns, subfoveal choroidal thickness 298 microns, 319 microns superiorly, 290 microns inferiorly, 192 microns nasally, and 294 microns temporally. Superior thickness was significantly greater (<.01) and nasal thickness significantly less (<.01) than subfoveal thickness. Subfoveal choroidal thickness was significantly correlated with age (r2=.07. P<.01), axial length (r2=.44, P<.01), refractive error (r2=.45, P<.01), however not with retinal thickness. Mean subfoveal scleral thickness was 317 microns, and was significantly correlated with subfoveal choroidal thickness (r2=0.40, P<.05), age (r2=0.21, P<.05), refractive error (r2=0.54, P<.01), but not with retinal thickness or axial length.
Conclusions:
Choroid is thinned according to the age, axial length, and refractive error. Choroid has a specific profile in its thickness dependent on the location. Sclera is also thinned according to the choroidal thinning
Keywords: choroid • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • retina