Cruickshank Fiona E, Logan Nicola S
School of Optometry, Life and Health Sciences, Aston University, Birmingham, UK.
Ophthalmic Physiol Opt. 2018 May;38(3):290-297. doi: 10.1111/opo.12457.
To gauge the extent to which differences in the refractive error axial length relationship predicted by geometrical optics are observed in actual refractive/biometric data.
This study is a retrospective analysis of existing data. Right eye refractive error [RX] and axial length [AXL] data were collected on 343 6-to-7-year-old children [mean 7.18 years (S.D. 0.35)], 294 12-to-13-year-old children [mean 13.12 years (S.D. 0.32)] and 123 young adults aged 18-to-25-years [mean 20.56 years (S.D. 1.91)]. Distance RX was measured with the Shin-Nippon NVision-K 5001 infrared open-field autorefractor. Child participants were cyclopleged prior to data collection (1% Cyclopentolate Hydrochloride). Myopia was defined as a mean spherical equivalent [MSE] ≤-0.50 D. Axial length was measured using the Zeiss IOLMaster 500. Optical modelling was based on ray tracing and manipulation of parameters of a Gullstrand reduced model eye.
There was a myopic shift in mean MSE with age (6-7 years +0.87 D, 12-13 years -0.06 D and 18-25 years -1.41 D), associated with an increase in mean AXL (6-7 years 22.70 mm, 12-13 years 23.49 mm and 18-25 years 23.98 mm). There was a significant negative correlation between MSE and AXL for all age groups (all p < 0.005). RX: AXL ratios for participant data were compared with the ratio generated from Gullstrand model eyes. Both modelled and actual data showed non-linearity and non-constancy, and that as axial length is increased, the relationship between myopia and axial length differs, such that it becomes more negative.
Optical theory predicts that there will be a reduction in the RX: AXL ratio with longer eyes. The participant data although adhering to this theory show a reduced effect, with eyes with longer axial lengths having a lower refractive error to axial length ratio than predicted by model eye calculations. We propose that in myopia control intervention studies when comparing efficacy, consideration should be given to the dampening effect seen with a longer eye.
评估在实际屈光/生物测量数据中，几何光学预测的屈光不正与眼轴长度关系的差异程度。
本研究是对现有数据的回顾性分析。收集了343名6至7岁儿童（平均7.18岁，标准差0.35）、294名12至13岁儿童（平均13.12岁，标准差0.32）和123名18至25岁年轻成年人（平均20.56岁，标准差1.91）的右眼屈光不正[RX]和眼轴长度[AXL]数据。使用日本新日本株式会社NVision-K 5001红外开放式自动验光仪测量远距离RX。儿童参与者在数据收集前使用睫状肌麻痹剂（1%盐酸环喷托酯）。近视定义为平均球镜当量[MSE]≤-0.50D。使用蔡司IOLMaster 500测量眼轴长度。光学建模基于光线追踪和对Gullstrand简化模型眼参数的操作。
平均MSE随年龄出现近视性偏移（6至7岁+0.87D，12至13岁-0.06D，18至25岁-1.41D），同时平均AXL增加（6至7岁22.70mm，12至13岁23.49mm，18至25岁23.98mm）。所有年龄组的MSE与AXL之间均存在显著负相关（所有p<0.005）。将参与者数据的RX:AXL比值与Gullstrand模型眼生成的比值进行比较。建模数据和实际数据均显示出非线性和非恒定性，并且随着眼轴长度增加，近视与眼轴长度之间的关系有所不同，变得更加负相关。
光学理论预测，眼轴较长时RX:AXL比值会降低。参与者数据虽符合该理论，但效果有所减弱，眼轴较长的眼睛其屈光不正与眼轴长度的比值低于模型眼计算预测值。我们建议，在近视控制干预研究比较疗效时，应考虑眼轴较长所产生的减弱效应。
