[Effects of nitric oxide on form-deprivation myopia in chicks].

Objective: To construct a chick model of form-deprivation myopia (FDM) to investigate the effect of nitric oxide (NO) on FDM.

Methods: FDM was induced in 60 one-day white leghorn chicks. They were divided into group A and B. One eye was covered randomly, and the other served as control. In each week of the experimental period, the retinoscopic refraction was performed, and the axial length was measured with A-mode ultrasound. The NO concentration of retina and choroid from the control and the experimental eyes was measured using NO detection kit. Change in the expression of iNOS mRNA was measured by RT-PCR. The activity of iNOS was analyzed with immunohistochemistry.

Results: Form-deprivation eyes were significantly more myopic than the controls, and the axial length of occluded eyes was significantly longer than that of the controls. Unocclusion attenuated the development of myopia and inhibited the axial elongation. Form-deprivation reduced the NO concentration ,the immunoreactivity of iNOS, and the expression of iNOS mRNA. The gradual restoration of normal vision was found after uncovering the eyes. But the expression of iNOS mRNA was significantly higher than that of the controls at the first week after the unocclusion.

Conclusion: Form-deprivation can construct an animal model of myopia. FDM is reversible before the chicks were mature. NO may be involved in the form of FDM.