Norton T T, McBrien N A
Department of Physiological Optics, School of Optometry/The Medical Center, University of Alabama, Birmingham 35294.
Vision Res. 1992 May;32(5):833-42. doi: 10.1016/0042-6989(92)90026-f.
The normal development of refractive state, ocular components and simple visually-guided behaviors was examined in maternally-reared tree shrews. Six groups consisting of 5 animals each were anesthetized and examined after 0, 15, 30, 45, 60 and 75 days of normal binocular visual exposure. Measures in the 75-day group provided values for an improved schematic eye of the tree shrew. Cycloplegic refraction showed a marked hyperopia (+25 D) at eye opening which decreased rapidly during the first 15 days of visual exposure and stabilized near the value (+5 D) expected in an eye of this axial length (approx. 7.8 mm). Corneal radius increased slightly during development. Anterior segment depth, measured by A-scan ultrasonography, seemed to complete most of its development at an earlier age (15-30 days of visual exposure) than did other ocular parameters. Lens thickness increased steadily throughout development. Vitreous chamber depth increased rapidly until 15 days of visual exposure, and then decreased because the lens thickness increased more rapidly than axial length. Crude orienting to, and following of, large objects developed shortly after eye opening (median age at onset, 5 and 6 days, respectively). Triggered visual placing responses developed at about the same time that the refractive state completed the rapid drop from highly hyperopic values. The slowed rate of ocular development after 15 days of visual exposure may be related to increased retinal activity that is permitted by neural maturation and by the presence of a relatively well-focussed retinal image. The increased activity may influence the final dimensions of the eye to coordinate the axial length with the focal length of the eye.
在由母兽抚养的树鼩中，研究了屈光状态、眼内结构和简单视觉引导行为的正常发育情况。将六组动物，每组5只，在正常双眼视觉暴露0、15、30、45、60和75天后进行麻醉并检查。75天组的测量结果为改进的树鼩模型眼提供了数据。睫状肌麻痹验光显示，睁眼时明显远视（+25 D），在视觉暴露的前15天迅速下降，并稳定在该眼轴长度（约7.8 mm）预期的值（+5 D）附近。角膜半径在发育过程中略有增加。通过A超超声测量的眼前节深度，似乎比其他眼参数在更早的年龄（视觉暴露15 - 30天）完成其大部分发育。晶状体厚度在整个发育过程中稳步增加。玻璃体腔深度在视觉暴露15天前迅速增加，然后下降，因为晶状体厚度的增加比眼轴长度更快。睁眼后不久就出现了对大物体的粗略定向和跟随行为（开始的中位年龄分别为5天和6天）。触发式视觉放置反应在屈光状态从高度远视值迅速下降完成时大约同时出现。视觉暴露15天后眼发育速率减慢可能与神经成熟和相对清晰聚焦的视网膜图像的存在所允许的视网膜活动增加有关。活动增加可能会影响眼睛的最终尺寸，以协调眼轴长度与眼睛焦距。
