Diurnal Variation in Choroidal and Retinal Thickness of the Early Treatment of Diabetic Retinopathy Study Macular Subfields Determined Using Swept-Source Optical Coherence Tomography.

PURPOSE: To describe diurnal variation in choroidal thickness (CT) and retinal thickness (RT) of the nine Early Treatment of Diabetic Retinopathy Study (ETDRS) macular subfields determined using swept-source optical coherence tomography.

METHODS

A prospective study was conducted on 24 healthy Korean volunteers who underwent two sequential measurements of a randomly selected eye at 9 a.m., 1 p.m., and 6 p.m. The radial scan mode was used. To determine the repeatability and reliability, we applied intragrader agreement using the intraclass correlation coefficient (ICC).

RESULTS

Significant diurnal variation in CT was observed. The highest mean CT was found at 9 a.m. The lowest mean CT occurred at 1 p.m. There was excellent intragrader agreement, with the ICC ranging from 0.961 to 0.997. There was no significant diurnal variation in RT.

CONCLUSION

There was significant diurnal variation in CT. The choroid was thinner at 1 p.m. than at 9 a.m. and 6 p.m.