AIM: To investigate the changes of visual development produced by monocular atropinization in rats.

METHODS: Twenty normal SD rats were randomly divided into two groups: control group(n=10)and atropinization(experimental)group(n=10). All the left eyes were selected as the experimental eyes, and the right eyes served as the normal eyes. The left eyes in atropinization group was produced by 1% atropine, 3 times a day and the right eyes in control group was treated with normal saline, 3 times a day. The flash visual evoked potentials(F-VEP)and retinoscopy refraction of the rats' both eyes were detected at five time points: 0, 7, 14, 21, and 28d after atropinization, respectively. After 28d, six rats were randomly selected from both groups and each group had three rats. The expression of the c-fos mRNA was observed in both visual cortexes. Another six rats were chosen for the same test after 2d dark environment with 2h light later. The expression of c-fos mRNA was detected again.

RESULTS: After 14d anisometropia was observed in experimental group, the difference was 3.9D(P<0.05), F-VEP P1 wave of the rats left in experimental group was reached to 88.9±1.889ms at 21d, there was statistical difference compared with the right eye(P<0.05). After 28d, c-fos mRNA expression in the left visual cortex of rats in the experimental group was higher than that of the right side, but there was no significant difference. But when underwent 2h light stimulation after in the darkroom 2d, the c-fos mRNA expression in in the left visual cortex of rats in the experimental group was 5 times higher than that of the right side, there was a statistically significant difference(P<0.05).

CONCLUSION: In the critical period of visual development, monocular chronic atropine in rats can form anisometropia, may delay the transmission of the optic nerve, hinder the normal development of the visual cortex. Monocular atropinization in rats can be used as the model of anisometropia.