Zhu Xiaoying, Park Tae Woo, Winawer Jonathan, Wallman Josh
Department of Biology, City College, City University of New York (CUNY), New York, New York 10031, USA.
Invest Ophthalmol Vis Sci. 2005 Jul;46(7):2238-41. doi: 10.1167/iovs.04-0956.
The fitting of chick eyes with positive or negative lenses causes eye growth to decelerate or accelerate, respectively, thereby minimizing the imposed blur. This study was conducted to determine whether the eye can initially assess the correct direction of growth or whether it relies on trial and error, reversing its direction if the magnitude of blur increases. The rapid changes in choroidal thickness in response to brief periods of defocus were measured.
After their eyes were measured by ultrasound biometry, chicks wore either a +10-D lens over one eye for 10 minutes while restrained in the center of a 60-cm drum (to ensure myopic blur), or a negative lens (-7 or -8.6 D) over one eye for 10 minutes or 1 hour in a normal cage environment. They were then kept in darkness until they were remeasured 2 hours, 1 day, or 2 days after the first measurement. Other chicks wore +10 or -8.6-D lenses briefly and were measured several times over the next 7 hours in darkness.
Wearing positive or negative lenses for only 10 minutes produced significantly different effects on choroidal thickness measured 2 hours later. Wearing positive lenses for 10 minutes caused an increase in choroidal thickness (in 28 of 32 eyes) and a concomitant decrease in vitreous chamber depth, relative to the amount of change in the untreated fellow eye over the same period. Wearing negative lenses for 1 hour caused significant changes in the opposite direction. Wearing lenses for 2 hours resulted in choroidal changes that persisted in darkness for up to 6 hours after positive lens wear, but returned to normal after negative lens wear. Finally, 1 hour of positive lens wear caused significant inhibition of ocular elongation over the next 2 days.
The eyes of chicks require only a brief period of lens wear to initiate compensation in the appropriate direction. Because the refractive status changes little during the period of lens wear, the authors conclude that eyes can rapidly determine the sign of the imposed blur without resorting to a trial-and-error method.
给雏鸡眼睛佩戴正透镜或负透镜会分别导致眼睛生长减速或加速，从而使所产生的模糊最小化。本研究旨在确定眼睛最初能否评估生长的正确方向，或者它是否依赖于试错法，即如果模糊程度增加就改变其生长方向。测量了脉络膜厚度对短时间散焦的快速变化。
通过超声生物测量法测量雏鸡眼睛后，将雏鸡一只眼睛佩戴 +10D 透镜 10 分钟，同时将其限制在 60 厘米鼓的中心（以确保近视性模糊），或者在正常笼养环境中一只眼睛佩戴负透镜（-7 或 -8.6D）10 分钟或 1 小时。然后将它们置于黑暗中，直到在首次测量后 2 小时、1 天或 2 天重新测量。其他雏鸡短暂佩戴 +10 或 -8.6D 透镜，并在接下来的 7 小时黑暗中多次测量。
仅佩戴 10 分钟正透镜或负透镜对 2 小时后测量的脉络膜厚度产生了显著不同的影响。与同期未处理的对侧眼睛的变化量相比，佩戴正透镜 10 分钟导致脉络膜厚度增加（32 只眼中的 28 只），同时玻璃体腔深度减小。佩戴负透镜 1 小时导致方向相反的显著变化。佩戴透镜 2 小时导致脉络膜变化，在佩戴正透镜后在黑暗中持续长达 6 小时，但在佩戴负透镜后恢复正常。最后，佩戴 1 小时正透镜在接下来的 2 天内对眼轴伸长产生了显著抑制。
雏鸡的眼睛仅需短暂佩戴透镜就能启动适当方向的补偿。由于在佩戴透镜期间屈光状态变化很小，作者得出结论，眼睛可以快速确定所产生模糊的符号，而无需采用试错法。
