[Comparison of retinal morphology and ultrastructure in defocus-induced myopia and form-deprivation myopia in rhesus monkeys].

OBJECTIVE

To investigate the changes of retinal ultrastructure of defocus-induced myopia and form-deprivation myopia in infant rhesus monkeys.

METHODS

A -3.00 D spectacle lens (n = 9) or diffuser lens (n = 6) was worn over one eye and a zero-powered lens over the fellow eye in 15 healthy rhesus monkeys ranging in age from 1 to 1.5 months. The eyes were examined periodically with corneal topography, cycloplegic retinoscopy, A-scan ultrasonography, and optical coherence tomography (OCT). Three months later, light and electron microscope were used to observe the changes of the retina.

RESULTS

In 15 monkeys, all eyes treated with -3.00 D spectacle lens or diffuser lens developed defocus-induced myopia or form-deprivation myopia. Not only defocus-induced myopia, but also form-deprivation myopia showed elongation of rod outer segment, decreased membrane disc of cone outer segment, increased clearance of the membrane disc and decreased thickness of the neurosensory retina (RNL) as compared with the control eyes (P < 0.05). There were no significant differences between the mean OCT and histomorphometric thickness of RNL and retinal pigment epithelium (RPE) after the correction of dehydration (P > 0.05).

CONCLUSIONS

There are significant differences in retinal ultrastructure between experimental myopic eyes and control eyes. But the morphological changes in the retina of the defocus-induced myopia showed no significant difference as compared with form-deprivation myopia. The role of changes of retinal ultrastructure in the development of myopia needs further studies. OCT can be used to examine the changes of RNL and RPE in experimental myopia in vivo.