The Effects of Illumination to Experimentally Induced Refractive Errors in the Chick

ABSTRACT

The effects of different luminance levels and light sources to emmetropization in the chick were investigaed. One-day-old, forty chicks were reared under condition of unilateral visual deprivation with translucent goggle. Under normal light cycles (12-h light/12-h dark), three kinds of luminance levels and two light sources (incandescent lamp vs fluorescent lamp) were used. Three weeks after hatching, refractive error, axial length, equator diameter and corneal diameter of the eyes were measured. The deprived eyes exhibited severe myopia of -11.94 diopters (p<0.001) and refractive changes were mainly related with axial elongations. Refractive error of 1000 lux group was less myopic than 2000 lux group (p<0.05). The fellow eyes didn't show significant difference between groups. No significant changes were noted between different light source groups. The experiment suggests that different degrees of illumination under normal light/dark environment can cause different refractive changes; More studies will be needed to show that the ideal luminance condition for emmetropization in our enviroment be present.