Purpose: To determine the diurnal variation in choroidal thickness and choriocapillaris flow measured by optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA) Methods: This study was a prospective study of 15 normal, y...
Purpose: To determine the diurnal variation in choroidal thickness and choriocapillaris flow measured by optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA) Methods: This study was a prospective study of 15 normal, young volunteers (30 eyes) who underwent OCT and OCTA examination 5 times a day at 2-hour intervals. Choroidal and choriocapillaris thicknesses were measured with the enhanced depth imaging mode of OCT. The area of flow was measured in 1-, 3-, and 6-mm-diameter areas centered at the fovea and analyzed with the split-spectrum amplitude- decorrelation angiography algorithm of OCTA. Choroidal and choriocapillaris thicknesses and flows were analyzed independently by two vitreoretinal specialists.
Results: Choroidal thickness showed a significant diurnal variation. The maximum thickness was 311.31 μm at 9 a.m., and the minimum thickness was 266.75 μm at 5 p.m. (p < 0.001). In contrast, the mean choriocapillaris thickness was 15.14 μm, and remained relatively constant without a significant diurnal variation (p = 0.694). The mean choriocapillaris flow area was 0.45 mm2 (p = 0.238) in a 1 mm area, 4.22 mm2 (p = 0.230) in a 3-mm diameter area, and 16.94 mm2 (p = 0.062) in a 6-mm diameter area. No diurnal variation was observed.
Conclusions: Despite significant diurnal variation in choroidal thickness, choriocapillaris thickness and flow remained relatively constant over time.