|Year : 2014 | Volume
| Issue : 4 | Page : 328-331
Effects of fasting on intraocular pressure in a black population
Mustapha B Hassan, Michaeline A Isawumi
Department of Surgery, Ophthalmology Unit, College of Health Sciences, Osun State University, Osogbo, Nigeria
|Date of Web Publication||4-Oct-2014|
Mustapha B Hassan
Department of Surgery, Ophthalmology Unit, College of Health Sciences, Osun State University, Osogbo
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Introduction: There is a dearth of literature available on the effects of fasting on Intraocular pressure (IOP) among all races and worldwide.
Objectives : To determine the effects of fasting on IOP in a black African population.
Materials and Methods: A population-based survey utilizing multistage random sampling techniques was carried out among healthy adult Muslims who were examined before and during Ramadan fast in Osogbo, Nigeria. Demographics were obtained, visual acuities, clinical examination of both eyes, and IOPs were done. Weights and waist circumference were measured. Data were analyzed using Statistical Package for Social Sciences ( SPSS) Version 16. Analysis generated frequencies and cross tabulations, whereas statistical significant values were derived using paired sample t-test and P < 0.05.
Results: A total of 60 subjects with 120 eyes were examined. Mean age was 42.3 years standard deviation (SD) 16.7, and the male to female ratio was 3:2. Majority were professionals (33.3%). Only 18.3% had less than secondary school education. Over 90% had normal vision (6/5-6/18). Before and during fasting, the mean weights were 65.92 kg SD 12.98 and 65.29 kg SD 12.41 with a reduction of 0.63 kg SD 3.82 (P = 0.214, 95% confidence interval (CI): 0.372-1.626); and the mean waist circumference was 87.20 cm SD 12.39 and 81.78 cm SD 11.65 (P = 0.000, 95% CI 4.128-6.720), respectively. Mean IOPs were 15.98 mmHg SD 3.11 and 14.08 mmHg SD 2.71 before and during fasting, respectively (P = 0.000, 95% CI 0.98558-2.82798).
Conclusions: The study shows that fasting significantly reduced IOP in an ocularly healthy black African population.
Keywords: Black, Fasting, Intraocular Pressure, Population
|How to cite this article:|
Hassan MB, Isawumi MA. Effects of fasting on intraocular pressure in a black population
. Middle East Afr J Ophthalmol 2014;21:328-31
|How to cite this URL:|
Hassan MB, Isawumi MA. Effects of fasting on intraocular pressure in a black population
. Middle East Afr J Ophthalmol [serial online] 2014 [cited 2019 Dec 12];21:328-31. Available from: http://www.meajo.org/text.asp?2014/21/4/328/142271
| Introduction|| |
Intraocular pressure (IOP) reflects the balance between the rate of aqueous formation by ciliary body and the rate of fluid exit from the eye through trabecular meshwork and uveoscleral outflow pathways. Normal IOP is taken as values between 10-21 mmHg by Applanation method. Factors affecting IOP include ambient temperature and time of the day, exercises, fluid intake, systemic and topical medications among others. Fasting has an effect on fluid intake and hence may impact negatively on IOP. It is also a well known fact that IOP is subjected to diurnal variation. The IOP becomes high in the morning and low in the evening, and this may actually be due to loss of body fluid as the day progresses.
Fasting is known to contribute to the reduction in fluid intake and hence affects internal body homeostasis, which may have effects on body hemodynamics, thereby affecting IOP either positively or negatively. Available few literatures have been seen only in the Oriental Asians and the Middle Eastern populations on this topic. ,,,, There has been paucity of data on studies among the Blacks and Caucasians. This study is intended to add to the scientific data base and literature on IOP and fasting among the black population. Future research and development can be planned following this.
| Materials and methods|| |
The study was carried out in Osogbo sometimes called "Ilu Aro" (home of dyeing), in Osun State, southwestern Nigeria-a trade center for a farming region. , According to population data of 1988, about 27% of the population were engaged in farming as their primary occupation, 8% were traders, and about 30% clerks and teachers. Most of the populations are members of the Yoruba ethnic group-one of the largest ethnic groups in west Africa, speaking Yoruba language. They are mainly Muslims, Christians, and of traditional religious adherents, and most of them engage in regular fasting as a religious obligation.
Materials and methods
This is a population-based survey to determine what effects fasting has on IOP in an ocularly healthy Black African population. The aim of the study was to find out the effect of fasting on IOP in a black healthy adult (above 15 years) African population in Osogbo, Nigeria, who observed fasting and also had no associated ocular pathologies like glaucoma, conjunctivitis, corneal scarring, uveitis, or any other disease that may affect IOP. Fasting in this case is defined as a period of at least 10 h without food and drinks.
Presurvey activities included seeking permission from and explaining the type and importance of the study to the sample population and the investigating team members. In the first stage of the sampling done by the principal investigator, the population was classified into those who intended to fast and those who did not intend to. The former were Muslims, hence the study was carried out among muslims during the Ramadan fast of year 2012. In the second stage, the town was then zoned into three-east, west, and north. One central mosque was selected in each zone randomly. On a day previously announced in each of the selected central mosque, health talk was given, the procedures to be carried out were explained, and written informed consent was obtained. The participants were then examined (by the ophthalmic team). Examination carried out involved visual acuity, IOP, anterior and posterior segment examination of the eye, as well as anthropometric measurements. Those who met the inclusion criteria after examination were then recruited into the study. Recruitment was done for the groups with intended fasting and those requiring no fasting.
Those recruited were given instructions that fasting meant abstinence from food and drinks for a period of at least 10 h.
This was to commence between 5.00 am in the morning, and 4.00 pm in the evening. In order to confirm who is actually fasting, weight in kilogram scale and waist circumference measured with tape rule in centimeters were recorded before and during fasting. These values were expected to reduce after fasting.
The data collection exercise also served as a free eye screening for the participants in the community.
Structured questionaire used to obtain information that bordered about demographies and previous ocular morbidity history, and examination findings was used to obtain the data. IOP measurements were taken in the evening time first before and also during the fasting period using Perkins Tonometer.
The data were entered into and analyzed using Statistical Package for the Social Sciences (SPSS) Version 16 software. Descriptive statistics involving frequencies and cross-tabulations were carried out, whereas statistically significant values were derived using paired sample t-test and P < 0.05.
Ethical clearance for this study was obtained from Osun State University Health Research Ethical Committee and written informed consent obtained from the participants.
| Results|| |
A total of 60 subjects were studied out of 200 that were screened during the prefasting and the fasting period. All were Muslims. The mean age was 42.3 ± 16.7 years with a range of 17-100 years. There were 36 (60%) males and 24 (40%) females. Majority of the subjects were professionals (33.3%). Only 18.3% had less than secondary education [Table 1]. Over 90% had 6/5-6/18 as their visual acuity in the better eye at presentation (normal according to World Health Organization (WHO) classification) [Table 2].
The mean weight before fasting was 65.92 ± 12.9 8 kg, whereas the mean weight during fasting was 65.29 ± 12.41 kg, with a difference (reduction) of 0.63 ± 3.82 kg. This reduction was not statistically significant as shown by paired sample t-test (P = 0.214, 95% confidence interval (CI): 0.372, 1.626). On the other hand, the mean waist circumference before fasting was 87.20 ± 12.39 cm, which dropped significantly to 81.78 ± 11.65 cm during fasting (P = 0.000, 95% CI: 4.128, 6.720). Similarly, the mean IOP before fasting was 15.98 ± 3.11 mmHg and during fasting reduced to 14.08 ± 2.71 mmHg. This reduction was also statistically significant (P = 0.000, 95% CI: 0.98558, 2.82798) [Table 3] and [Table 4].
As the data collection exercise also served as a free screening exercise for the participants, some potentially blinding diseases that may be amenable to treatment like cataract, glaucoma, diabetic retinopathy, and refractive errors were detected and were subsequently referred for prompt treatment to the nearby government health institutions where such treatment could be obtained.
| Discussion|| |
Fasting is a condition whereby people are subjected to deprivation from food and drink for a certain period of hours during the day (usually more than 6 h to allow for a complete gastric emptying) as opposed to starvation where people are denied food and water for long period of time usually days or months as a result of famine, war, or other natural disasters. A lot of people engage in regular fasting as a fulfillment of their religious vows. It is therefore necessary to take into consideration whether a patient is fasting or not when presenting for routine consultation in our day to day clinics. Fasting is also associated with some degree of dehydration hence with a consequent effect on body homeostasis. 
All the participants reported in this study were Muslims. Some Christians and traditional religion adherents were recruited at the initial phase but dropped out because they refused to fast when the second phase of data collection exercise was to commence.
The age range cut across the young, middle-aged, and the elderly with a male preponderance. This shows that any age group from the adolescent period can partake in fasting. This male preponderance is attributed to the fact that health seeking behavior is skewed toward the males in some traditional African society as most females have to seek permission from their husband to access healthcare. , In comparison, Fotouhi et al., reported in 2006 that the Middle Eastern population had more men than women who sought eye care.
The study also showed that majority of the participants was professionals with higher education. This may just be coincidental. It could also be that their level of education informed their level of response toward participation in the project. This could be similar to several other studies that have shown that education has a positive effect on the utilization of eye care services and a better health seeking behavior than among the illiterates. ,,,
In this study, evidence of fasting was derived from the significant reduction in waist circumference and a nonsignificant decrease in observed weights of the participants. These measurements were used to confirm whether the study participants actually went on fasting.
The result of this study shows that fasting has a significant reduction effect on IOP in blacks with no associated ocular pathology. This compares with Kerimoglu et al., in Turkey  and Dadeya et al., in India  in similar studies investigating effects of fasting on IOP in the Middle Eastern populations.
On the other hand, Assadi et al., in Iran and Li et al., in China found no difference between IOP measured during fasting and nonfasting conditions. , Inan et al., in Turkey found a decrease, but this decrease was not statistically significant. 
Also, the prompt referral of some potentially blinding diseases detected in the populace will thus help in preventing blindness in the community and the burdens associated with it.
| Conclusion|| |
The results of this study show that fasting has a significant reduction effect on the IOP in an ocularly healthy black population. The possible mechanism for this reduction could be the dehydration effects of fasting, as fasting has been shown to cause dehydration;  however, further studies still need to be carried out to confirm this and also consider the possibility of other hypotheses like decreased choroidal circulation and so forth.
Therefore, fasting and dehydration conditions should be taken into consideration when interpreting measured IOP values in the day to day clinic, especially during religious fasting periods.
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[Table 1], [Table 2], [Table 3], [Table 4]