Choroidal Thickness, Photoreceptor Thickness, and Retinal Vascular Caliber Alterations in Dark Adaptation

Our aim was to evaluate the alterations of subfoveal choroidal thickness (SFCT), photoreceptor layer thickness (PRT), and retinal vessel diameter in the dark and light adaptation.

Twenty-four eyes of 24 healthy volunteers (12 males, 12 females) were included in this cross-sectional and observational study. The SFCT, PRT, retinal arteriole, and venule caliber measurements were performed with spectral domain optical coherence tomography in the dark (0.0 cd/m²) and under light (80 cd/m²) adapted conditions.

The mean age of the participants was 30.4 ± 4.4 years (range: 22-42). The SFCT increased statistically significantly in dark adaptation (p < 0.001), then returned to baseline values following light adaptation. The PRT, retinal arteriole, and venule caliber measurements were similar in the dark and light (p > 0.05).

While SFCT increased, PRT, and retinal vessel diameter did not change following transition from light to dark.