Michel J. Shami, MD (Lubbock, TX), Ronald P. Danis, MD (Madison, WI), Diabetic Retinopathy Clinical Research Network


To evaluate diurnal variation in Optical Coherence Tomography (OCT) measured retinal thickness in patients with center-involved diabetic macular edema (DME).


Ninety-six subjects with DME were recruited at 25 centers participating in the Diabetic Retinopathy Clinical Research Network ( In 156 eyes with clinically-diagnosed DME and OCT central subfield (CSF) retinal thickness =?225 microns at 8 a.m., OCT was used to measure CSF thickness at 6 time points over a single day between 8 a.m. and 4 p.m. We calculated the proportion of eyes meeting the composite endpoint of a change in CSF
thickening (observed CSF thickness minus the mean normal CSF thickness) of at least 25% and of at least 50 microns at two consecutive time points or between 8 a.m. and 4 p.m. ETDRS visual acuity was measured at 8 a.m., 12 p.m., and 4 p.m.


At 8 a.m., the mean central subfield thickness was 368 microns and the mean visual acuity was 66 letters (approximately 20/50). Five eyes of 4 subjects (3% of eyes, 95% CI, 1% to 8%) had a decrease in central subfield thickening (as defined above) while 2 eyes of 2 subjects (1%, 95% CI, 0% to 5%) had an increase in central subfield thickening of this same magnitude. The mean change in relative CSF retinal thickening between 8 a.m. and 4 p.m.
was a decrease of 6% (95% CI -9% to -3%) and the mean absolute change was a decrease of 13 microns (95% CI -17 to -8). The absolute change was significantly greater in retinas that were thicker at 8 a.m. (P < 0.001) but the relative change was not (P=0.14). Change in retinal thickening from 8 a.m. to 4 p.m. had poor correlation with change in visual acuity (r=- 0.05), reflecting the large proportion of eyes with little change in thickening and the variability inherent in the measurements of both acuity and retinal thickening.


Although on average there are slight decreases in retinal thickening during the day, most eyes with DME have little meaningful change in OCT central subfield thickness between 8a.m. and 4p.m. Supported by NEI grants U10 EY14231, 5 U10 EY14269-03, 5 U10 EY14229.