Evaluation of the Effect of Religious Fasting on Retinal Vessel Density and Retinal Thickness Using Optical Coherence Tomography Angiography.

We conducted this study to assess the effect of religious fasting on intraocular pressure (IOP) as well as retinal parameters and retinal thickness during Ramadan using optical coherence tomography angiography (OCTA) performed on a spectral domain device. All the participants ate a pre-dawn meal and drink, and then fasted for at least 15 hours. We assessed a total of 61 eyes from 31 healthy volunteers with a mean age of 32.87 ± 8.07. A significant decrease was found in the median IOP after fasting at 10.00 mmHg in comparison with the pre-fasting value of 12.00 mmHg (p < .0001). Retinal peri-papillary capillary (RPC) whole image, RPC inside disk, and RPC mean values showed significant decreases after fasting (p = .011, .012, and .032 respectively). RPC whole vessel density (VD), RPC inside VD, and RPC VD mean values also showed significant decreases after fasting period (p = .025, <.0001, and .003, respectively). Religious fasting during the warm season could decrease IOP. It could also reduce the blood flow of the retina, specifically the macula, and the retinal peri-papillary VD.