Guo S S, Sivak J G, Callender M G, Herbert K L
School of Optometry, University of Waterloo, Ontario, Canada.
Ophthalmic Physiol Opt. 1996 Nov;16(6):486-90.
It is possible to induce ametropias in young chicks either by depriving the developing eye of clear form vision with a translucent goggle or by defocusing the retinal image with convex or concave lenses. The refractive properties of the developing chick eye are also altered by raising young birds in a continuous light environment. The effects of superimposing form deprivation or defocus treatments on chicks raised in continuous light are unclear. Newly hatched (n = 31) chicks were raised for 2 weeks under continuous light while wearing either translucent goggles or + 10 or -10 diopter (D) lenses over one eye. Refractive states, corneal curvature and intraocular dimensions were measured periodically by retinoscopy, keratometry and A-scan ultrasound. The birds were sacrificed after 2 weeks and the eyes removed and measured with calipers. Under continuous light, all eyes treated with translucent goggle and -10 D lens developed moderate myopia (-2.6 +/- 0.5 D and -1.4 +/- 0.3 D, respectively) by day 4. The eyes treated with a + 10 D lens developed moderate hyperopia (+ 4.8 +/- 0.5 D) at day 4. Corneal curvatures of all treated eyes were slightly, but significantly, larger than contralateral control eyes by day 4. After 2 weeks of goggle or lens application, all the treated eyes were hyperopic due to corneal flattening. But the eyes treated with a goggle or a -10 D lens still showed relative myopia compared to the fellow eyes (treated minus untreated = -3.8 +/- 0.4 D and -2.8 +/- 0.4 D, respectively), and the eyes treated with a + 10 D lens showed more hyperopia than fellow eyes (treated minus untreated = + 5.1 +/- 0.6 D). Compared with the control eyes, the axial length (mainly vitreous chamber depth) was slightly, but significantly, increased in the eyes treated with a goggle or a -10 D lens, and the axial length decreased slightly in the eyes treated with + 10 D lens. The results suggest that form deprivation and retinal defocus (induced by +/- 10 D lenses) could still induce experimental refractive errors (myopia and hyperopia) in chicks kept under continuous light, but the effects of form deprivation and retinal defocus were partially suppressed by continuous light.
通过用半透明眼罩剥夺发育中的眼睛的清晰形态视觉，或用凸透镜或凹透镜使视网膜图像散焦，有可能在幼雏中诱发屈光不正。在持续光照环境中饲养幼鸟也会改变发育中的雏鸡眼睛的屈光特性。在持续光照下饲养的雏鸡上叠加形态剥夺或散焦处理的效果尚不清楚。将刚孵出的（n = 31）雏鸡在持续光照下饲养2周，同时在一只眼睛上佩戴半透明眼罩或+10或-10屈光度（D）的镜片。通过检影验光、角膜曲率测量和A超超声定期测量屈光状态、角膜曲率和眼内尺寸。2周后处死雏鸡，取出眼睛并用卡尺测量。在持续光照下，到第4天时，所有用半透明眼罩和-10 D镜片处理的眼睛都出现了中度近视（分别为-2.6±0.5 D和-1.4±0.3 D）。用+10 D镜片处理的眼睛在第4天时出现了中度远视（+4.8±0.5 D）。到第4天时，所有处理过的眼睛的角膜曲率比未处理的对侧眼睛略大，但差异显著。在佩戴眼罩或镜片2周后，由于角膜变平，所有处理过的眼睛都出现了远视。但是，与未处理的对侧眼睛相比，佩戴眼罩或-10 D镜片处理的眼睛仍表现出相对近视（处理眼减去未处理眼分别为-3.8±0.4 D和-2.8±0.4 D），而用+10 D镜片处理的眼睛比未处理的对侧眼睛表现出更多的远视（处理眼减去未处理眼为+5.1±0.6 D）。与对照眼睛相比，佩戴眼罩或-10 D镜片处理的眼睛的眼轴长度（主要是玻璃体腔深度）略有增加，但差异显著，而用+10 D镜片处理的眼睛的眼轴长度略有减少。结果表明，形态剥夺和视网膜散焦（由±10 D镜片诱发）仍可在持续光照下饲养的雏鸡中诱发实验性屈光不正（近视和远视），但持续光照部分抑制了形态剥夺和视网膜散焦的影响。
