[Influence of optical defocus and form deprivation on the emmetropization of infant rhesus monkeys]

Abstract

Purpose: To investigate the influence of optical defocus and form deprivation on the emmetropization of infant rhesus monkeys.

Methods: Twenty-two normal infant rhesus monkeys, between 20 and 40 days of age, were divided into 2 groups of A (n=13) and B (n=9) by random. The monkeys from group A and B wore diffuser and -3.00 D spectacle lens over their right eyes. All the animals wore 0.00 D lens over their left eyes as control. The monkeys' refractive error, corneal topography, the depth of vitreous chamber were measured at the start of lens wear and at 2, 4, 6, 8, 12 weeks post-treatment. By these means, we can observe the changes of eye growth and refractive status dynamically.

Results: Among all the animals, there was no significant difference between the right and left eyes in vitreous chamber length at the start of lens wear (P > 0.05). During the course of observation, the vitreous chamber of all the animals elongated gradually. At 12 weeks post-treatment, the axial eyeball elongation of the treatment eyes of group A was more obvious than that of the control eyes (P < 0.01). As for group B, there was no apparently significant difference in vitreous chamber length between the right eyes and the left eyes at 12 weeks post-treatment (P > 0.05). But we can still find the vitreou chamber elongation of the treatment eyes was faster than that of the control eyes in this group. All the monkeys were hyperopic and there was no significant difference between their two eyes at the start of lens wear (P > 0.05). During the course of lens wear, all the eyes became less and less hyperopic. At 12 weeks post-treatment, the treatment eyes exhibited relative or absolute myopic status as compared with the fellow eyes both in group A and group B (P < 0.05). In the course of observation, the diopter of simulated keratorefraction (Sim K) value in all eyes decreased with time passing. No remarkable difference was found between the right and left eyes in Sim K value before and after lens wear in both of the two groups (P > 0.05).

Conclusions: Under the condition of optical defocus and form deprivation, the treated eyes exhibited relative or absolute myopic status mainly because of the faster growth of vitreous chamber. It implies that these two methods can intervene the process of emmetropization of infant rhesus monkeys.