Effect of form-deprivation myopia on optic nerve head and retinal morphology in guinea pigs

Abstract

Objective To evaluate the effect of form deprivation myopia on optic nerve head and retinal morphology in guinea pigs using optical coherence tomography (OCT). Methods Twenty guinea pigs aged from 4 to 5 weeks were chosen and randomly divided into the experimental group and control group, with 10 guinea pigs in each group. Form deprivation myopia was established for the right eyes of guinea pigs in experimental group for 4 weeks. The guinea pigs of control group were not intervened. Before and 4 weeks after form deprivation, refraction was measured by retinoscopy after cycloplegia; the axial length was measured by A-scan ultrasound; retinal nerve fiber layer (RNFL) thickness, optic nerve head and retinal morphology of guinea pigs were analyzed using OCT. Results Before form deprivation, there were no statistically significant differences in spherical equivalent, axial length, RNFL thickness, disc edge area, optic disc area, average cup disc ratio, vertical cup disc ratio, cup volume, retinal thickness, or retinal volume between the experimental group and control group of guinea pig (P>0.05). After 4 weeks of form deprivation, RNFL thickness of (64.9±17.7) μm in guinea pigs in experimental group was thinner compared to (97.9±25.1) μm in control group (t=-2.845, P=0.015). Retinal thickness of (142.7±3.4) μm in guinea pigs in experimental group was thicker compared to (138.4±3.5) μm in control group (t=2.338, P=0.038). There were no significant differences in disc edge area, optic disc area, average cup disc ratio, vertical cup disc ratio, cup volume or retinal volume between groups (P>0.05). There were statistically significant differences in spherical equivalent, axial length, RNFL thickness, vertical cup to disc ratio cup volume, and retinal thickness between after and before form deprivation in the right eye of guinea pigs in the experimental groups (t=46.001, -50.119, 5.385, 3.447, -2.814, -8.911; P 0.05). Conclusion Form deprivation myopia has an effect on RNFL and retinal thickness. Key words: Myopia/complications; Optic disk/physiopathology; Retina/physiopathology; Animal experimentation