ABSTRACT
Globally, physical inactivity is an important risk factor for the development of non-communicable disease consisting of coronary artery disease, as well as, other diseases including hypertension, diabetes, obesity, osteoporosis, and certain types of cancers. Parasympathetic nervous system (PNS) activity in the eye is determined by the pupil cycle time (PCT) can be comparable with cardiac parasympathetic response and thereby determine the morbidity and mortality among individuals. The PCT is measured by throwing white light on the edge of the pupil. Pupil cycling is a feature of pupillary reflex arc. The aim of this study is to establish the effect of physical activity on the PCT. The counting of PCT was done for 90 cycles and average one count is considered a single PCT. The physical activity level (PAL) was determined by administering a physical activity level questionnaire developed in the Division of Nutrition, St. John’s Medical College, Bangalore. The PAL is classified as <1.4 as sedentary, 1.55 to 1.75 moderately active, and >1.75 heavily active. Thirty healthy male volunteers in the age group of 18-50 years and with BMI of 18.5 kg/m2–30 kg/ m2 were studied. We obtained PCT of 962.00±105.72 msec in sedentary, 896.77±85.88 msec in moderately active and 889.45±68.71 msec in heavily active individuals. Linear regression analysis shows there is statistically significant difference between the three different groups of physical activity level with a b value of 0 and R2 being 0.19. Increase in physical activity led to decrease in the PCT i.e. increase in the parasympathetic tone in the eye. Pupil cycle time (PCT) is a simple noninvasive tool to assess and differentiate the PNS function in different activity level of individual.
ABSTRACT
Pupil cycle time (PCT) is a simple way to measure the parasympathetic activity in the eye. This is a sensitive and specific test for the study of parasympathetic function. The cardiac parasympathetic tone is a good indicator to predict morbidity and mortality in an individual. The PCT is correlated with cardiac parasympathetic tone. In the present study we have aimed to look at the PCT in different nutritional status in human subjects. Sixty-three healthy adult male volunteers in the age group of 18–50 yrs were studied. They were divided in three groups based on their BMIs as undernourished, normal and preobese/obese. The mid-arm circumference (MAC) and waist- hip ratio (W:H) are incorporated as adjuvant to strengthen that they are divided into three different nutritional groups. The PCTs of undernourished (818±145 ms), normal control (904±63 ms) and overweight (991±106 ms) is expressed as mean and SD (P<0.001). A linear regression analysis was performed taking BMI, MAC, W:H and PCT as parameters, which shows a positive linear correlation. The results showed that the PNS activity in the eye is greatly modulated in different states of nutrition. Pupil cycle time is a simple, noninvasive investigative tool to assess and differentiate the PNS function in obese and chronic undernourished subjects.