Purpose: To investigate diurnal fluctuations in retinal thickness using spectral domain optical coherence tomography (SD-OCT).
Methods: Spectralis SD-OCT was used to obtain data from the right eye of 21 healthy subjects (mean age, 31.3 years) at 7 AM, 1 PM, and 7 PM. For each eye, a full peripapillary retinal nerve fiber layer circular scan and a 19-line horizontal raster scan (6- by 6-mm area) centered on the fovea were performed.
Results: Retinal nerve fiber layer thickness was greater at 7 AM or 1 PM than at 7 PM for nasal (79.1 μm [1 PM] vs. 77.6 [7 PM]; p = 0.024), inferior (134.1 [7 AM] vs. 131.9 [7 PM]; p = 0.009), and inferonasal (115.2 [7 AM] vs. 115.6 [1 PM] vs. 112.4 [7 PM]; p < 0.001) subfields. Macular thickness was greater at 7 AM than at 7 PM for inferior 6 mm (290.2 μm [7 AM] vs. 287.8 [7 PM]; p < 0.001) ETDRS (Early Treatment Diabetic Retinopathy Study) subfield. Macular volume was greater at 7 AM than at 7 PM for nasal 3 mm (0.541 mm3 vs. 0.538; p = 0.028) and inferior 6 mm (1.538 vs. 1.525; p < 0.001) ETDRS subfields. The remaining studied areas did not show any significant change throughout the day.
Conclusions: The Spectralis SD-OCT retinal thickness measurements showed a small but statistically significant diurnal variation in nasal and inferior subfields toward smaller values in the evening. However, the overall change is close to the instrument’s resolution and repeatability.
Poostchi Ophthalmology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran.
Mohammad H. Nowroozzadeh Poostchi Ophthalmology Research Center Poostchi Eye Clinic Zand Street Shiraz, Iran e-mail: email@example.com