[Effects of experimentally induced hyperopic optical defocus on refractive status of adolescent monkeys].
OBJECTIVE
To determine if chronic optical defocus alters refractive development in monkeys at ages corresponding to the typically developed age of myopia in human children.


METHODS
A hyperopic anisometropia was produced in 7 adolescent rhesus monkeys by photorefractive keratectomy (PRK). The laser procedures were performed when the monkeys were 2.0 to 2.5 years old, which corresponded to approximately 8-10 years old in human being. The ocular effects of the induced anisometropia were assessed periodically by corneal topography, retinoscopy and A-scan ultrasonography.


RESULTS
By about 30 days post-PRK, the experimentally induced refractive errors was stabilized and the treated eyes were between +0.75 and +2.25 D more hyperopic than their fellow eyes. Subsequently, 7 monkeys showed systematic reductions in the degree of anisometropia. Although some regression in corneal power occurred, the compensating refractive changes were primarily due to the differences in vitreous chamber growth (r = 0.74, P = 0.046).


CONCLUSIONS
Vision-dependent mechanisms that are sensitive to refractive error are still active in adolescent primates and probably play a role in maintaining stable refractive errors in the two eyes. Consequently, conditions that result in consistent hyperopic defocus could potentially contribute to the development of juvenile onset myopia in children.
Zhong
Xing-wu
XW
Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China. xingzh88@hotmail.com
Ge
Jian
J
Chen
Xiao-lian
XL
Tan
Gang
G
Nie
Hao-hui
HH
D000818:Animals; D015858:Anisometropia / Q000503:physiopathology*; D048988:Corneal Surgery, Laser; D006956:Hyperopia / Q000503:physiopathology*; D008253:Macaca mulatta; D009216:Myopia / Q000503:physiopathology