Gibson George A, Cruickshank Fiona E, Wolffsohn James S, Davies Leon N
Ophthalmic Research Group, Life and Health Sciences, Aston University, Birmingham B4 7ET, UK.
Vision (Basel). 2018 Aug 21;2(3):33. doi: 10.3390/vision2030033.
This study aimed to quantify biometric modifications of the anterior segment (AS) during accommodation and to compare them against changes in both accommodative demand and response. Thirty adults, aged 18-25 years were rendered functionally emmetropic with contact lenses. AS optical coherence tomography (AS-OCT) images were captured along the 180° meridian (Visante, Zeiss Meditec, Jena, Germany) under stimulated accommodative demands (0-4 D). Images were analysed and lens thickness (LT) was measured, applying a refractive index correction of 1.00. Accommodative responses were also measured sequentially through a Badal optical system fitted to an autorefractor (Shin Nippon NVision-K 5001, Rexxam, Japan). Data were compared with Dubbelman schematic eye calculations. Significant changes occurred in LT, anterior chamber depth (ACD), lens centroid (i.e., ACD + LT/2), and AS length (ASL = ACD + LT) with accommodation (all < 0.01). There was no significant change in CT with accommodation ( = 0.81). Measured CT, ACD, and lens centroid values were similar to Dubbelman modelled parameters, however AS-OCT overestimated LT and ASL. As expected, the accommodative response was less than the demand. Interestingly, up until approximately 1.5 D of response (2.0 D demand), the anterior crystalline lens surface appears to be the primary correlate. Beyond this point, the posterior lens surface moves posteriorly resulting in an over-all sigmoidal trajectory. he posterior crystalline lens surface demonstrates a sigmoidal response with increasing accommodative effort.
本研究旨在量化调节过程中眼前节（AS）的生物特征变化，并将其与调节需求和反应的变化进行比较。30名年龄在18 - 25岁的成年人通过佩戴隐形眼镜达到功能性正视。在刺激调节需求（0 - 4D）下，沿180°子午线（Visante，蔡司医疗技术公司，耶拿，德国）采集AS光学相干断层扫描（AS - OCT）图像。对图像进行分析并测量晶状体厚度（LT），应用折射率校正值1.00。还通过安装在自动验光仪（日本瑞萨电子公司生产的Shin Nippon NVision - K 5001）上的巴德尔光学系统依次测量调节反应。将数据与杜贝尔曼示意图眼计算结果进行比较。随着调节，LT、前房深度（ACD）、晶状体质心（即ACD + LT/2）和AS长度（ASL = ACD + LT）发生了显著变化（均P < 0.01）。调节时CT无显著变化（P = 0.81）。测量的CT、ACD和晶状体质心值与杜贝尔曼模型参数相似，然而AS - OCT高估了LT和ASL。正如预期的那样，调节反应小于调节需求。有趣的是，直到大约1.5D的反应（2.0D需求），晶状体前表面似乎是主要相关因素。超过这一点，晶状体后表面向后移动，导致总体呈S形轨迹。晶状体后表面随着调节力增加呈现S形反应。
