Zhou Xiangtian, Qu Jia, Xie Ruozhong, Wang Ruiqing, Jiang Liqin, Zhao Hailan, Wen Jiquan, Lu Fan
School of Ophthalmology and Optometry, Eye hospital, Wenzhou Medical College, 82 Xueyuan Road, Wenzhou, Zhejiang 325003, China.
Vision Res. 2006 Sep;46(18):2815-23. doi: 10.1016/j.visres.2006.01.027. Epub 2006 May 24.
This study investigated changes in refraction, corneal curvature, axial components and weight of posterior sclera in guinea pig eyes during the normal development from birth.
Sixty-four guinea pigs were assigned to eight groups (n=8 each). Each group underwent a series of ocular measurements at one of the eight time-points (0, 1, 2, 3, 5, 7, 9 and 11 weeks), including refraction (streak retinoscopy), corneal radius of curvature (CRC; keratometry), anterior segment length (AS: corneal thickness and depth of the anterior chamber), thickness of the crystalline lens (CL), vitreous chamber length (VC; all A-scan ultrasonography) and dry weight of a circular 6mm diameter punch in the posterior sclera (electronic balance). Results of all the measurements were statistically compared between right eye and left eye, male and female and among different age groups. Artifacts of retinoscopy due to small eye artifact were also estimated at different ages.
The refraction in guinea pig eyes was +5.22+/-0.23 D (Mean, SE) at birth. This value decreased rapidly during the first 3 weeks followed by a slow decline. The overall decrease in refraction was highly significant from birth to 11 weeks (p<0.001 one way ANOVA). The small eye artifact was approximately 4.00 D at birth, which reduced to 2.76 D at 11 weeks. The guinea pig eyes were emmetropic by 3 weeks of age when the small eye artifact was taken into account. The CRC (3.24+/-0.01 mm at birth), AS (1.20+/-0.01 mm at birth), CL (2.72+/-0.03 mm at birth) and VC (3.28+/-0.01 mm at birth) increased within the first 3 weeks despite a transient decrease in the CRC within the first week. The increase in CRC, CL and VC continued after 3 weeks, however, the AS remained constant after this age. The increase in VC was better correlated to the decline of hyperopia (R(2)=0.70) than the other components (R(2)=0.33-0.39). Dry weight of the posterior sclera increased linearly from birth (p<0.001 between any two close time-points from 3 to 9 weeks) and had a moderately linear correlation with the VC (R(2)=0.60). There were no significant differences between the right eye and left eye or between male and female in all the measurements.
In guinea pigs, the hyperopia present at birth rapidly reduces to emmetropia within the first 3 weeks of age. The emmetropization process in guinea pigs is mainly related to the increase in the vitreous chamber length. This relationship in guinea pigs is similar to that in chickens, tree shrews, primates and humans. The axial development of the vitreous chamber in guinea pigs appears to be associated with tissue growth of the posterior sclera.
本研究调查了豚鼠眼睛从出生到正常发育过程中屈光、角膜曲率、眼轴各组成部分以及后巩膜重量的变化。
64只豚鼠被分为八组（每组n = 8）。每组在八个时间点（0、1、2、3、5、7、9和11周）之一进行一系列眼部测量，包括屈光（带状检影法）、角膜曲率半径（CRC；角膜曲率计测量）、眼前节长度（AS：角膜厚度和前房深度）、晶状体厚度（CL）、玻璃体腔长度（VC；均采用A超超声测量）以及后巩膜直径6mm圆形样本的干重（电子天平测量）。对所有测量结果在右眼和左眼、雄性和雌性以及不同年龄组之间进行统计学比较。还评估了不同年龄时因小眼球假象导致的检影误差。
豚鼠出生时眼睛的屈光为+5.22±0.23 D（平均值，标准误）。该值在出生后的前三周迅速下降，随后缓慢下降。从出生到11周，屈光的总体下降非常显著（单因素方差分析，p < 0.001）。出生时小眼球假象约为4.00 D，到11周时降至2.76 D。考虑小眼球假象后，豚鼠眼睛在3周龄时变为正视。出生时的CRC（3.24±0.01 mm）、AS（1.20±0.01 mm）、CL（2.72±0.03 mm）和VC（3.28±0.01 mm）在前三周内增加，尽管第一周内CRC有短暂下降。3周后，CRC、CL和VC继续增加，但此后AS保持不变。与其他组成部分（R² = 0.33 - 0.39）相比，VC的增加与远视的下降相关性更好（R² = 0.70）。后巩膜干重从出生起呈线性增加（3至9周之间任意两个相邻时间点比较，p < 0.001），并且与VC有中度线性相关性（R² = 0.60）。所有测量中，右眼和左眼之间以及雄性和雌性之间均无显著差异。
在豚鼠中，出生时存在的远视在出生后的前三周内迅速降至正视。豚鼠的正视化过程主要与玻璃体腔长度的增加有关。豚鼠的这种关系与鸡、树鼩、灵长类动物和人类相似。豚鼠玻璃体腔的轴向发育似乎与后巩膜的组织生长有关。
