[Comparison on morphology and ultrastructure of two kinds of myopic models]

To study the possibility of inducing refractive errors by opening the mouse (C57BL/6J) eye artificially after birth and explore the difference in pathogenic mechanism in form-deprivation myopia by analyzing the histological changes of the animal eyes.

4-day-old mice (n = 13) was undergone 10-day monocular artificially opened period till the opposite eye was natural open. Another group 12-day-old mice (n = 13) were raised with monocular suture of eyelid for 7 days. Age-matched untreated mice were used as control. Retinoscopic refraction was performed subsequently. Animals were sacrificed and the eyes enucleated at the end of the experiment. The axial length and weight of the eyes were measured and the sections of the eyes were also observed by light and electron microscope.

All eyes treated with two methods showed significant development of myopia compared with the contralateral eye. The axial length was elongated in form deprived eyes, but it was shortened in artificially opened eyes; no change in the weight of eyeball was found in form deprived eyes, but it was reduced in artificially opened eyes when compared with corresponding fellow eyes. Under light microscope, there is no significant histological difference observed in the eyes treated with two methods. Under electron microscope, rod outer segment in form deprived eyes was inordinate and the phagosomes containing fractions of the membrane disc of outer segment were remarkably decreased. No significant changes of photoreceptor were demonstrated in artificially opened eyes.

The means of artificially opening eyelid can induce myopia in the mouse and the method may be useful to establish myopia animal model.