Investigation of the effects of Islamic fasting on ocular parameters

TFOS Lifestyle: Impact of nutrition on the ocular surface

Nutrients, required by human bodies to perform life-sustaining functions, are obtained from the diet. They are broadly classified into macronutrients (carbohydrates, lipids, and proteins), micronutrients (vitamins and minerals) and water. All nutrients serve as a source of energy, provide structural support to the body and/or regulate the chemical processes of the body. Food and drinks also consist of non-nutrients that may be beneficial (e.g., antioxidants) or harmful (e.g., dyes or preservatives added to processed foods) to the body and the ocular surface. There is also a complex interplay between systemic disorders and an individual's nutritional status. Changes in the gut microbiome may lead to alterations at the ocular surface. Poor nutrition may exacerbate select systemic conditions. Similarly, certain systemic conditions may affect the uptake, processing and distribution of nutrients by the body. These disorders may lead to deficiencies in micro- and macro-nutrients that are important in maintaining ocular surface health. Medications used to treat these conditions may also cause ocular surface changes. The prevalence of nutrition-related chronic diseases is climbing worldwide. This report sought to review the evidence supporting the impact of nutrition on the ocular surface, either directly or as a consequence of the chronic diseases that result. To address a key question, a systematic review investigated the effects of intentional food restriction on ocular surface health; of the 25 included studies, most investigated Ramadan fasting (56%), followed by bariatric surgery (16%), anorexia nervosa (16%), but none were judged to be of high quality, with no randomized-controlled trials.

Intermittent Fasting to the Eye: A New Dimension Involved in Physiological and Pathological Changes

Intermittent fasting (IF) is gaining popularity as a therapeutic dietary strategy that regulates metabolism and can alter the development of metabolic disorders. An increasing amount of research has connected ocular diseases to IF and discovered that it has a direct and indirect effect on the eye’s physiological structure and pathological alterations. This article summarizes the progress of research on IF in regulating the physiological structures of the ocular vasculature, the anterior segment of the eye, the retina, and the choroid. We explored the therapeutic potential of IF for various common ocular diseases. In the future, a comprehensive study into the fundamental processes of IF will provide a direct and rigorous approach to eye disease prevention and therapy.

Effect of fasting on diurnal fluctuation of parafoveal and peripapillary vessel density and related oculodynamic and haemodynamic parameters

PURPOSE

To investigate the effects of Ramadan fasting on diurnal superficial-deep parafoveal vessel density (pfVD) and nerve head (NH)-radial peripapillary capillary (RPC) peripapillary vessel density (ppVD) using optical coherence tomography angiography (OCTA), as well as other related oculodynamic and haemodynamic parameters, and to compare these findings with those in the nonfasting period in healthy individuals.

METHODS

A total of 105 healthy individuals, 42 women and 63 men, were included in this prospective study. OCTA was used to examine the superficial-deep pfVD and NH-RPC ppVD. In the third week of Ramadan, OCTA readings were obtained twice daily at 08:00 and 16:00 hour (h) under fasting conditions and compared with nonfasting values 2 weeks after Ramadan. Both intraocular pressure (IOP) and blood pressure values were assessed accordingly.

RESULTS

The mean age (23-51) of individuals was 34.37 ± 7.04 years. In comparison with the 08:00 -h values, the 16:00 -h IOPs, superficial-deep pfVDs and RPC ppVDs were substantially reduced both during the fasting and nonfasting periods (P = 0.001, P = 0.009, P = 0.006, P = 0.006, P = 0.004, P = 0.004, P = 0.41, P = 0.032 and P = 0.021). No differences were found in the diurnal change of superficial-deep pfVDs, NH-RPC ppVDs, IOPs and mean ocular perfusion pressures (MOPPs) between the fasting and nonfasting periods, whereas the same was not true for mean arterial blood pressures (MABPs) (P = 0.049).

CONCLUSIONS

The parafoveal and peripapillary VDs (except for NHpp-VD) and IOPs were found to have decreased significantly throughout the day both in fasting and nonfasting periods. Our study confirms the diurnal changes in the IOPs, MOPPs, superficial-deep pfVDs and NH-RPC ppVDs under dehydration and normal terms.

Evaluation of the effect of fasting on intraocular pressure, anterior segment parameters and density of crystalline lens and cornea

PURPOSE

To evaluate the effect of fasting on anterior chamber depth, anterior chamber volume and corneal and lens density by Scheimpflug technology and to measure intraocular pressure changes.

METHODS

Totals of 50 healthy fasting individuals in Ramadan (study group) and 50 healthy non-fasting subjects (control group) were included. Central corneal thickness (CCT), anterior chamber depth (ACD), anterior chamber volume (ACV), corneal density (CD) and lens density (LD) were evaluated with Scheimpflug technology. Intraocular pressure (IOP) was measured with applanation tonometry. Both eyes of each participant were examined and also compared.

RESULTS

Comparison of groups: There was a statistically significant difference between CD, ACD, ACV and IOP (respectively, right/left eye: fasting: CD: 12.81 ± 0.76/12.73 ± 0.73; ACD: 2.92 ± 0.37 mm/2.93 ± 0.37 mm; ACV: 168.3 ± 41.82 mm³/183.34 ± 32.46 mm³; IOP: 13.80 ± 1.22 mmHg/14.88 ± 2.73 mmHg; non-fasting: CD: 13.28 ± 1.01/13.17 ± 0.77; ACD: 3.06 ± 0.31 mm/3.07 ± 0.31 mm; ACV: 167.46 ± 42.92 mm³/180.68 ± 31.45 mm³; IOP: 13.60 ± 1.65 mmHg/14.74 ± 2.93 mmHg) values on the right side (p < 0.01, p = 0.03, p = 0.04, p = 0.01, respectively). Although there was a statistically significant difference between the ACV, CD and IOP values on the left side (p < 0.01, p = 0.03, p = 0.01, respectively), no statistical significance was found for the ACV value on the left side (p = 0.08).

CONCLUSION

The results demonstrated that, while fasting did not lead to any change in LD and CCT, it caused a small decrease in ACD and ACV, and a significant decrease in CD and IOP values. Scheimpflug technology seems to be a valuable tool for the evaluation of anterior segment changes in patients who are fasting.