Diurnal variation in choroidal thickness in relation to sex, axial length, and baseline choroidal thickness in healthy Korean subjects

PURPOSE: To investigate diurnal variations in choroidal thickness (CT) in relation to various factors in healthy Korean subjects using spectral-domain optical coherence tomography. METHODS: A prospective study was conducted on 100 healthy volunteers who each underwent measurements of CT in the same subfoveal area using an enhanced depth imaging technique with spectral-domain optical coherence tomography at 8 AM, 11 AM, 2 PM, and 5 PM. Possible correlations between the diurnal variation of CT and other factors, such as sex, axial length (AL), baseline CT (8 AM), blood pressure, and intraocular pressure, were evaluated. RESULTS: One hundred volunteers with a mean age of 30.1 years were scanned. A significant pattern of diurnal variation was observed, with a mean CT of 278.28 ± 91.78 μm at 8 AM, 271.57 ± 89.08 μm at 11 AM, 266.39 ± 86.18 μm at 2 PM, and 264.92 ± 87.10 μm at 5 PM in a right eye. Right eye and left eye had a similar trend of diurnal cycle. Based on sex, AL, and baseline CT, the pattern of diurnal variation was greater and the amplitude significantly was greater in men, AL ≤ 24 mm and baseline CT ≥ 300 μm (men vs. women: P = 0.048, AL ≤ 24 mm vs. AL > 24 mm: P = 0.036, baseline CT ≥ 300 μm vs. baseline CT < 200 μm: P = 0.002, baseline CT ≥ 300 μm vs. 200 μm ≤ baseline CT < 300 μm: P = 0.008). There were no significant correlations between the diurnal variation of CT and systolic blood pressure, diastolic blood pressure, or intraocular pressure. CONCLUSION: In men as well as in those with a shorter AL and thick baseline CT, a greater pattern of diurnal variation with significantly greater amplitude was observed.