Difference in Morning and Evening Choroidal Thickness in Japanese Subjects With No Chorioretinal Disease

BACKGROUND AND OBJECTIVE: To determine whether the choroidal thickness varies significantly according to the time of measurement in Japanese subjects without chorioretinal diseases. PATIENTS AND METHODS: Twelve eyes of 12 subjects were examined with enhanced depth imaging spectral-domain optical coherence tomography. The choroidal thickness was measured in the mornings (9: 00 to 9: 30 AM) and evenings (7: 30 to 8: 00 PM) at three locations: the fovea, 1.5 mm temporal to the fovea, and 1.5 mm nasal to the fovea. RESULTS: The mean age of the subjects was 62.6 +/- 14.5 years. For the morning measurements, the mean choroidal thickness was 308.5 +/- 74.4 mu m at the fovea, 276.2 +/- 84.6 mu m temporally, and 239.3 +/- 98.4 mu m nasally. For the evening measurements, the mean choroidal thickness was 328.8 +/- 85.6 mu m at the fovea, 284.8 +/- 91.6 mu m temporally, and 248.9 +/- 101.5 mu m nasally. The mean subfoveal (P < .0001) and nasal (P = .03) choroidal thicknesses were significantly thicker in the evenings than in the mornings. There was no significant difference in the mean temporal choroidal thickness (P = .08). CONCLUSION: The choroidal thickness varies according to the time of measurement.