IMPACT OF EXERCISE ON INTRAOCULAR PRESSURE IN RELATION TO BODY MASS INDEX

Background and Objective: Intraocular pressure varies throughout the night and day. The diurnal variation for normal eyes is between 3 and 6mmHg and the variation may increase in glaucomatous eyes. Hence, we wanted to investigate the effect of exercise on intraocular pressure changes in relation with Body Mass Index. Materials and Methods: The effect of exercise on intraocular pressure and blood pressure was evaluated in our clinical laboratory in 30 voluntary 1 year Medical students of Kasturba Medical College Bejai, Mangalore after the institutional ethical clearance. Materials used in the study were schizont tonometer, Measuring tape, Weighing Scale, treadmill and Paracaine eye drops. After a resting period, the subjects height and weight was recorded, Paracaine eye drops were instilled in both the eyes and then intraocular pressure recorded using Schizont Tonometer after 2 min so that anaesthetics acts. Then they were asked to walk on treadmill with average speed till they were exhausted, again intraocular pressure was noted as above with all aseptic precautions. The statistical analysis was done using students unpaired ttest using SPSS software Results were expressed in terms of mean and standard deviation. p value was taken significant at 5 percent confidence level (p<0.05). Results: Intraocular pressure was measured according to BMI under two groups, first with group having BMI less than 22 and other in group having BMI more than 22. There was a significant decrease in intraocular pressure after exercise in group two with BMI more than 22. Gender wise comparison of intraocular pressure both before and after exercise did not reveal much significance. Blood pressure was also recorded both before and after exercise which did not reveal any significance in relation to BMI. Conclusion: From our study we conclude that exercise has significantly decreased the intraocular pressure and has a correlation with body mass index in young age group.


Introduction
Intraocular pressure (IOP) is the fluid pressure inside the eye. Intraocular pressure is mainly determined by the coupling of the production of aqueous humor and the drainage of aqueous humor mainly through the trabacular meshwork located in the anterior chamber angle. Intraocular pressure measurement is also influenced by corneal thickness and rigidity 1 . Ocular hypertension is defined by intraocular pressure being higher than normal, in the absence of optic nerve damage or visual field loss. Current consensus in ophthalmology defines normal intraocular pressure as that between 10 mmHg and 20mmHg 2 .The average value of intraocular pressure is 15.5mmHg with fluctuations of about 2.75 mmHg. Hypotony, or ocular hypotony, is typically defined as intraocular pressure equal to or less than 5 mmHg. Such low intraocular pressure could indicate fluid leakage and deflation of the eyeball 3 . Intraocular pressure varies throughout the night and day. The diurnal variation for normal eyes is between 3 and 6mmHg and the variation may increase in glaucomatous eyes. Physical exercise produced a decreased intraocular pressure without significant change in facility of outflow or episcleral venous pressure. The diminution in intraocular pressure was associated with an increased serum osmolarity, but it was believed that this did not account completely for the change. The physiological changes in the eye during exercise are not fully understood. Some

Material and Methods
The effect of exercise on intraocular pressure and Body Mass Index was evaluated in our clinical laboratory in 30 voluntary students of 1 st year Medical students of Kasturba Medical College Bejai, Mangalore. All individuals were in the age group 18-25 years. Healthy subjects who were not suffering from any infectious diseases or any diseases of eye, non diabetic between age group of 18-25 years were included in the present study. Individuals with a history of eye diseases, history of diabetes, past history of medical illness and above 25 or below 18 years of age were excluded. Materials used in the study were schizont tonometer, Sphygmomanometer, treadmill, measuring tape, weighing scale and Paracaine eye drops. The students arrived at clinical laboratory, Department of physiology in the morning between 10.00-11.0AM. They were requested to come in a relaxed condition and quiet mood. The temperature in the laboratory was between 25 degree Celsius. They were also asked to fill a questionnaire including type of diet consumed whether vegetarian or mixed and physical activity performed on a daily basis, their habit like alcohol etc were noted. After a resting period, the subjects were asked to lie down in supine position on couch and their Blood pressure was recorded, Paracaine eye drops were instilled in both the eyes and then intraocular pressure recorded using Schizont Tonometer after 2 min so that anaesthetic acts then they were asked to walk on treadmill with average speed till they were exhausted, again their blood pressure, intraocular pressure were noted as above with all aseptic precautions then their results were noted in the Proforma. Their height in cms and weight in Kgs were noted. The Body mass index was calculated by the formula, BODY

Statistical Analysis:
The statistical analysis was done using students unpaired T test using SPSS software Results were expressed in terms of mean and standard deviation. P value was taken significant at 5 percent confidence level (p<0.05).

Results
Intraocular pressure was measured according to BMI under two groups as shown in Table-2 First with group having BMI less than 22 and other in group having BMI more than 22. There was a significant decrease in intraocular pressure after exercise in group two with BMI more than 22. Gender wise comparison of intraocular pressure both before and after exercise did not reveal much significance as shown in Table-1 and Fig-1. Blood pressure was also recorded both before and after exercise which did not reveal any significance in relation to BMI as shown in Table -3.

Discussion
This study was conducted with the aim of determining whether acute exercise has any effect on intraocular pressure and to determine how the various exercise protocols affect these changes in the intraocular pressure. In our study BMI was also included as a parameter. Comparison of intraocular pressure before and after exercise in relation to BMI showed a significant decrease in subjects whose BMI was >22 as shown in Table-1. The probable reason may be that obesity cause increase in systolic blood pressure leading to decrease in IOP. Further, it is showed that the relationship between intraocular pressure and obesity, IOP value was slightly higher in males than in females also supports the result of the present study. Normally glaucoma is detected at later age; though degenerative changes may begin to occur at younger age itself. In short our study suggest that early screening at younger age and regular isokinetic exercise may help to prevent glaucoma So isokinetic exercise may also be consider as one of the adjuvant to treatment for glaucoma which is one of the leading cause of blindness in the world. The reduction of IOP after exercise has IJBAR (2012) 03 (01) www.ssjournals.com been the subject of various investigations [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] .
In normal subjects the intraocular pressure decreases during exercise 31 , and its reduction is proportional to the work load 32 . In the present high-powered study we observed that in all groups there was an IOP reduction after aerobic exercise regardless of antiglaucoma eye drop instillation. The present study confirms the fall in intraocular pressure in human beings seen after exercise (33)(34)(35). This might be due to a significant rise in blood lactate, a concomitant increase in plasma osmolarity, and a lowering of blood pH (36)(37)(38) . The maximum fall in intraocular pressure and changes in blood chemistries occur immediately following exercise. At 30 minutes, blood pH and plasma osmolarity return to baseline levels, while blood lactate is still elevated and intraocular pressure is still decreased. These changes in blood chemistry after exercise are similar to other reported studies (36)(37)(38). The increase of plasma osmolarity is greater immediately after exercise and is associated with a decrease in blood pH. The increase in blood lactate immediately after exercise does not account for the entire observed increase in plasma osmolarity.
Other factors, such as hemoconcentration and dehydration, account for the greater osmolarity rise seen after exercise (39). In summary we can say that our study shows that exercise has significantly decreased the intraocular pressure and has a correlation with body mass index in young age group.