Sulley Anna, Osborn Lorenz Kathrine, Wolffsohn James S, Young Graeme
Johnson & Johnson Vision Care Companies, Wokingham, UK.
Johnson & Johnson Vision Care, Inc, Jacksonville, FL, USA.
Cont Lens Anterior Eye. 2017 Aug;40(4):248-252. doi: 10.1016/j.clae.2017.04.001. Epub 2017 May 11.
To calculate theoretical fitting success rates (SR) for a range of typical soft contact lens (SCL) designs using a mathematical model.
A spreadsheet mathematical model was used to calculate fitting SR for various SCL designs. Designs were evaluated using ocular topography data from 163 subjects. The model calculated SR based on acceptable edge strain (within range 0-6%) and horizontal diameter overlap (range 0.2-1.2mm). Where lenses had multiple base curves (BCs), eyes unsuccessful with the steeper BC were tested with the flatter BC and aggregate SR calculated. Calculations were based on typical, current, hydrogel and silicone hydrogel SCLs and allowed for appropriate on-eye shrinkage (1.0-2.3%). Theoretical results were compared with those from actual clinical trials.
Theoretical success rates for one-BC lenses ranged from 60.7% (95% CI 7.2%) to 90.2% (95% CI 3.7%). With two-BC designs, most combinations showed a SR increase with a second BC (84.0%-90.2%). However, one of the two-BC combinations showed only negligible increase with a second BC (72.4%-73.0%). For designs with lower SR, the greatest contributor to failure was inadequate lens diameter. For a given design, differences in shrinkage (i.e. on-eye bulk dehydration) had a significant effect on success rate. In comparison with historical clinical data, there was a positive correlation between small lens fitting prevalence and discomfort reports (r=+0.95, P=<0.001) with a poor correlation between theoretical and actual tight/loose fittings.
Mathematical modelling is a useful method for testing SCL design combinations. The results suggest that judicious choice of additional fittings can expand the range of fitting success.
使用数学模型计算一系列典型软性接触镜（SCL）设计的理论拟合成功率（SR）。
使用电子表格数学模型计算各种SCL设计的拟合SR。利用163名受试者的眼部地形图数据对设计进行评估。该模型基于可接受的边缘应变（0 - 6%范围内）和水平直径重叠（0.2 - 1.2毫米范围内）计算SR。对于具有多个基弧（BC）的镜片，对较陡BC拟合失败的眼睛用较平的BC进行测试，并计算总体SR。计算基于典型的、当前的水凝胶和硅水凝胶SCL，并考虑了适当的眼上收缩（1.0 - 2.3%）。将理论结果与实际临床试验结果进行比较。
单BC镜片的理论成功率范围为60.7%（95%CI 7.2%）至90.2%（95%CI 3.7%）。对于双BC设计，大多数组合显示随着第二个BC的增加SR升高（84.0% - 90.2%）。然而，其中一种双BC组合随着第二个BC的增加仅显示出可忽略不计的升高（72.4% - 73.0%）。对于SR较低的设计，导致失败的最大因素是镜片直径不足。对于给定的设计，收缩差异（即眼上总体脱水）对成功率有显著影响。与历史临床数据相比，小镜片拟合患病率与不适报告之间存在正相关（r = +0.95，P = <0.
