Aim: In this study, we aimed to evaluate the effects of Ramadan fasting on retinal vascular and anterior chamber parameters. Materials and Methods: The study included 60 healthy eyes of 30 volunteers (15 males, 15 females) who visited our clinic between May and July 2017. We performed measurements of intraocular pressure (IOP), anterior chamber volume (ACV), central corneal thickness (CCT), central macular thickness (CMT), optic disc retinal nerve fiber layer (OD-RNFL) and subfoveal choroidal thickness (SFCT) and retinal vascular analysis (the central retinal artery equivalent [CRAE], central retinal vein equivalent [CRVE], and artery-to-vein ratio [AVR]). The measurements were repeated in the 4th and 12th hours of the daily fasting period and 1st postprandial hour on the last 5 days of the Ramadan month, and one month after the Ramadan month. Results: The mean participant age was 29.30±8.12 years. The twelfth-hour SFCT, CRAE, and CRVE measurements were statistically significantly lower than the values measured one month after Ramadan (p=0.033, p=0.020, p=0.025, respectively). However, no statistically significant difference was observed in the IOP, ACV, CCT, CMT, OD-RNFL, and AVR measurements. Discussion and Conclusion: We found that fasting for 12 hours or longer caused changes in retinal vessel diameter and choroidal thickness.