Effect of yoga on visual perception and visual strain

Abstract

Visual perception implies that additional features of a visual stimulus are extracted and cognized. Yoga practice improved the response to a flickering light stimulus, so that it continues to be perceived as ‘flickering’ (rather than fused) at higher frequencies. This response was observed in both children and adults when the ‘critical flicker fusion frequency’ was measured at the end of the yoga programme compared to before. Following yoga, the degree of optical illusion perceived (using the Müller–Lyer lines) was also reduced. A recent randomized controlled trial on 118 professional computer users, randomized as yoga and wait-list control groups, showed that two months of yoga practice reduced subjective reports of symptoms of dry eye and objective evidence of visual fatigue in these professionals. Hence, yoga practice has potential applications especially in those occupations requiring good visual perceptual sensitivity and minimal visual strain.

Acknowledgements

The authors gratefully acknowledge the support from Dr H.R. Nagendra and Dr R. Nagarathna of Vivekananda Yoga Research Foundation, Bangalore, and the Director, Central Council for Research in Yoga and Naturopathy, New Delhi, India