Beresford J A, Crewther S G, Kiely P M, Crewther D P
School of Optometry, University of New South Wales, Sydney, Australia.
Optom Vis Sci. 2001 Jan;78(1):40-9. doi: 10.1097/00006324-200101010-00013.
Simultaneous comparisons of the circumferential morphological tissue profiles and final refractions from form-deprivation myopia (FDM), defocus-induced myopia (DIM), and defocus-induced hyperopia (DIH) models of ametropia have been made to test the hypothesis that changes in the thickness profiles of the three coats of the eye, and particularly that of the choroid, can be predicted from the degree of induced refractive error.
Hatchling chickens (n = 23) were raised for 2 weeks wearing either a monocular translucent diffuser (FDM, n = 8), monocular -10.00 D lens goggle (DIM, n = 7), monocular +10.00 D lens goggle (DIH, n = 7), or nothing (Norm, n = 1). All animals were refracted using retinoscopy and were then sacrificed, and whole eyes were processed for scanning electron microscopy. Retinal, choroidal, and cartilaginous sclera (CS) thickness measurements were made from photographic collages of the entire circumference of the globe. Of the 23 chickens, complete morphological profile data were available for both eyes of 10 animals (nine treated and one normal). The contralateral fellow eyes (FEyes) of all nine experimental chickens were used as experimental controls as paired comparisons for statistical analyses.
Morphological profiles of control and experimental eyes revealed significant systematic regional variations in tissue thickness. This variation was related to nasal or temporal eccentricity with the nasal side generally thinner than the temporal. Retinal, choroidal, and CS tissue from FDM and DIM eyes showed very similar anatomical responses despite significantly different degrees of refractive change. DIH eyes showed significant increases in choroidal thickness but none in retinal or CS thickness. Analysis of fellow control eyes indicated that in both myopia models (FDM and DIM), significant changes in all tissues of the untreated fellow eyes occur whereas only the choroid of the fellow eye was affected in the hyperopic (DIH) model.
The morphological similarity observed in the circumferential profiles of the retina, choroid, and cartilaginous sclera of the FDM and DIM eyes despite approximately 20 D difference in final refraction suggests that choroidal thickness is not a good predictor of final refractive error across models. Similarly, the final refractive difference of approximately 20 D between the DIM and the DIH eyes did not receive a major contribution from the final difference in choroidal thickness (with its implied effect on vitreous chamber length).
同时比较形觉剥夺性近视（FDM）、离焦性近视（DIM）和离焦性远视（DIH）三种屈光不正模型的圆周形态组织轮廓和最终屈光状态，以检验以下假设：眼睛三层结构，尤其是脉络膜厚度轮廓的变化，可以根据诱导屈光不正的程度来预测。
将孵化出的小鸡（n = 23）饲养2周，其中单眼佩戴半透明扩散器（FDM，n = 8）、单眼佩戴-10.00 D镜片眼罩（DIM，n = 7）、单眼佩戴+10.00 D镜片眼罩（DIH，n = 7），或不做处理（正常组，n = 1）。所有动物均通过检影验光测量屈光状态，然后处死，将全眼进行处理以用于扫描电子显微镜检查。通过眼球全周的照片拼贴测量视网膜、脉络膜和软骨性巩膜（CS）的厚度。在23只小鸡中，10只动物（9只处理组和1只正常组）的双眼均获得了完整的形态轮廓数据。所有9只实验小鸡的对侧眼（FEyes）用作实验对照，进行配对比较以进行统计分析。
对照眼和实验眼的形态轮廓显示组织厚度存在明显的系统性区域差异。这种差异与鼻侧或颞侧偏心度有关，鼻侧通常比颞侧薄。尽管屈光变化程度明显不同，但FDM和DIM眼的视网膜、脉络膜和CS组织显示出非常相似的解剖学反应。DIH眼的脉络膜厚度显著增加，但视网膜或CS厚度没有增加。对对照侧眼的分析表明，在两种近视模型（FDM和DIM）中，未处理的对侧眼所有组织均发生了显著变化，而在远视（DIH）模型中，仅对侧眼的脉络膜受到影响。
尽管最终屈光相差约20 D，但在FDM和DIM眼的视网膜、脉络膜和软骨性巩膜的圆周轮廓中观察到形态相似性，这表明脉络膜厚度并非所有模型中最终屈光不正的良好预测指标。同样，DIM和DIH眼之间约20 D的最终屈光差异，并非主要由脉络膜厚度的最终差异（及其对玻璃体腔长度的潜在影响）所致。
