Purpose:
To determine the effects of 430nm and 530nm monochromatic light on refractive development and retinal-cone distribution and density in guinea pigs.
Methods:
Eighteen guinea pigs (two-week old) were randomly distributed to blue-light group (BL), green-light group (GL) and white-light group (WL, as a control) (n=6 for each). In BL and GL, guinea pigs were reared in monochromatic light of 430nm (blue) and 530nm (green) respectively. The illuminative parameters of all groups were identical and the light quantum number was 3×10-4µmol·cm-2·s-1. All groups underwent biometric measurement including refraction, axial length and etc. before and after twelve-week treatment. All animals were used for retinal-cone immunocytochemistry finally.
Results:
There were no significant differences among groups in the biometric measurements prior to exposure in different illuminations (one way ANOVA: p>0.05). After twelve-week exposure, the eyes of GL were induced myopia for about -1.5D (P<0.001), and about +3.2D hyperopia (P<0.001) was induced in BL. The results of retinal-cone immunocytochemistry indicated that the density of ventral M-cone in GL (8496.3±499.6/mm2) increased (WL 5637.8±388.5/mm2, P<0.01), while the dorsal M-cone density in BL (12872.2±854.2/mm2) decreased (WL 15641.4±685.2/mm2, P<0.05). The S-cone density of BL increased significantly (P<0.05) in all three zones, dorsal (3037.4±103.8/mm2vs.834.6±87.7/mm2), central (17942.4±887.4/mm2vs.15697.9±764.8/mm2) and ventral (18043.7±785.1/mm2vs.16746.6±849.1/mm2). But, the density of S-cone in GL decreased significantly (P<0.01) all over, dorsal (384.6±94.2/mm2), central (10596.6±683.5/mm2) and ventral (11439.5±733.4/mm2).
Conclusions:
430nm and 530nm monochromatic light could influence the refractive development and meanwhile change the distribution and density of the retinal-cones in guinea pigs. There may be a relationship between the refractive change and the shift of the cone distribution and density, and the cones may play a role in the ametropia induced by monochromatic lights.
Keywords: photoreceptors • emmetropization • color vision