The effect of various levels of stroboscopic illumination on the growth of guinea pig eyes

Abstract

Background: The aim was to investigate various levels of stroboscopic illumination effect on the growth of guinea pig eyes.

Methods: Thirty-six two-week-old guinea pigs were randomised to one of three treatment groups (n = 12 for each). Two stroboscopic-reared groups were raised with a duty diurnal cycle of 50 per cent at a flash rate of 0.5 Hz. Illumination intensity varied between zero-to-250 lux or zero-to-500 lux during each cycle in each group, respectively. The third control group was exposed to 250 lux illumination. Refraction and biometric measurements were taken for each animal prior to and after two, four, six and eight weeks of treatment. Finally, retinal microstructure was examined.

Results: There was significant correlation between refractive errors and axial elongation. After eight weeks of treatment, illumination with flickering light 0-250 lux caused a larger myopic shift with increased axial length than illumination of continuous 250 lux. Stroboscopic illumination with zero-to-500 lux caused a further myopic shift and longer axial length than stroboscopic illumination with zero-to-250 lux. In animals raised in flickering light of zero-to-250 lux or zero-to-500 lux for eight weeks, the outer segment disc membranes in photoreceptor layers were found deformed and detached.

Conclusion: Chronic exposure to low-frequency temporally modulated illumination-induced histological damage in the retina and induced exaggerated axial length elongation.

Keywords: eye development; guinea pig; luminance; refractive state; stroboscopic illumination.