The Influence of Growth on Experimental Myopia in Tree Shrews

The object of this study was to clarify the ocular structural changes of tree shrews during development and the influence of growth on experimental myopia. Eighty-four eyes of 42 tree shrews (43–1604 days old) were included. The body weight was measured. The axial length was measured using A-mode ultrasonography, and the mean value of both eyes was calculated. Monocular form deprivation (FD) was induced in 13 8-week-old tree shrews. The axial length and refractive error were measured before and at 15, 30,45, 60, 90, and 120 days after FD was induced. The body weights increased rapidly from birth until 100 days, the point at which tree shrews reach maturity. The ocular structures changed rapidly during this period, except for the anterior chamber depth. In the animals with FD, myopia increased rapidly by 45 days following FD at approximately 100 days after birth. However, after this time, myopia increased slowly. Almost the same results were found for the vitreous cavity and the axial length. Our study demonstrated that ocular structural growth changes markedly to the point at which tree shrews reach maturity, and FD myopia may be influenced by ocular growth.