Investigation of the effects of Islamic fasting on ocular parameters

Purpose: To investigate the effects of religious fasting during the month of Ramadan on intraocular pressure (IOP), refractive error, corneal tomography and biomechanics, ocular biometry, and tear film layer properties. Methods: This prospective study was carried out one week before and in the last week of Ramadan. Ninety-four eyes of 94 healthy adult volunteers (54 males and 40 females) with a mean ± SD age of 35.12 ± 9.07 were enrolled in this study. Patients with any systemic disorder, ocular disease, or a history of previous surgery were excluded. Corneal tomography and biomechanics, ocular biometry, IOP, refractive error, and tear break up time (TBUT) were evaluated in non-fasting and fasting periods by the Pentacam (Oculus), Corvis ST (Oculus), IOL Master (Carl Zeiss), computerized tonometer (Topcon CT-1/CT-1P), auto kerato-refractometer (Topcon KR-1), and Keratograph 5M (Oculus), respectively. Results: There was no significant difference in the central corneal thickness (CCT) between the study groups (P ¼ 0.123) using the Pentacam while the Corvis ST showed a significant difference in all participants (P < 0.0001). Moreover, the peak distance (distance of the two surrounding peaks of the cornea at the highest concavity) of male and female participants showed a significant difference between the fasting and non-fasting groups (P ¼ 0.002). The anterior chamber depth (ACD) using the Pentacam decreased in the male group (P ¼ 0.004) in the fasting period. During the fasting period, computerized tonometer showed a decrease in IOP only in males in comparison to the non-fasting group (P ¼ 0.018) while the Corvis ST showed decreased IOP in all participants (P < .0001). The steep keratometry (K2) in the corneal posterior surface appeared to be different in males between the study groups (P ¼ 0.034). We were unable to show any significant difference in other ocular parameters between fasting and non-fasting periods. Conclusion: This study showed that ACD, IOP, CCT, and peak distance were different between fasting and non-fasting groups while no difference was observed in other ocular parameters. Interpretations of these significant differences should be considered in the clinical setting.