English

Abstract

BACKGROUND: Visual acuity is the resolving power of eyes which enables to distinguish the details and shapes of the objects. It is influenced by the intensity (illumination) of light falling on the object. Measuring visual acuity is a simple test in assessing-health of the eyes, the pathway and visual brain. Intact normal vision is mandatory for selection of posts related to driving and traffic services. Intactness of visual acuity is influenced by a number of factors and one among them is intensity of ambient light. Hence, this study is undertaken to assess optimum light intensity for better visual perception. AIM: To evaluate the association between visual acuity and intensity of light and the optimum intensity of light to carry out for better perception of vision. MATERIALS AND METHODS: 100 literate subjects 50 males and 50 females between 15-45 years, act both as cases and controls. Subjects, instructed to read alphabets and numbers from Snellen chart in 15 watts, 20 watts, 40 watts, 60 watts, 100 watts, 200 watts were considered as the study group and the same subjects in this study in day light as controls. Chart was placed at 6m distance. Both right and left eyes were tested separately in dark room illuminated with controlled light intensities. Number of correct characters read were noted for different illuminations and compared with that of controls. RESULTS: Reduced illumination significantly increased the no of incorrect choices and was statistically significant (P < 0.05) between 15 100 W. Visual acuity was best in 200 W in comparison with day light but was not statistically significant. However Visual acuity showed no significant difference between males and females for different intensities of light.