College of Optometry, University of Houston, Houston, Texas.
Optom Vis Sci. 2020 Sep;97(9):732-740. doi: 10.1097/OPX.0000000000001577.
To achieve maximum visual benefit, wavefront-guided scleral lens corrections (WGCs) are aligned with the underlying wavefront error of each individual eye. This requirement adds complexity to the fitting process. With a view toward simplification in lens fitting, this study quantified the consequences of placing WGCs at two pre-defined locations.
This study aimed to quantify performance reduction accompanying the placement of the WGC at two locations: (1) the average decentered location (ADL; average decentration observed across individuals wearing scleral lenses) and (2) the geometric center (GC) of the lens.
Deidentified residual aberration and lens translation data from 36 conventional scleral lens-wearing eyes with corneal ectasia were used to simulate WGC correction in silico. The WGCs were decentered from the eye-specific pupil position to both the ADL and GC locations. The impact of these misalignments was assessed in terms of change (from the aligned, eye-specific pupil position) in higher-order root mean square (HORMS) wavefront error, change in log of the visual Strehl ratio (logVSX), and predicted change in logMAR visual acuity (VA).
As expected, HORMS increased, logVSX decreased, and predicted VA was poorer at both ADL and GC compared with the aligned condition (P < .001). Thirty-four of 36 eyes had greater residual HORMS, and 33 of 36 eyes had worse logVSX values at the GC than at the ADL. In clinical terms, 19 of 36 eyes at the ADL and 35 of 36 eyes at the GC had a predicted loss in VA of three letters or greater.
The placement of the WGC at either ADL or GC is predicted to lead to a noticeable reduction in VA for more than half of the eyes studied, suggesting the simplification of the fitting process is not worth the cost in performance.
为了获得最大的视觉效果，波前引导巩膜镜片矫正（WGC）与每个人眼的基础波前误差相匹配。这一要求增加了适配过程的复杂性。为了简化镜片适配，本研究量化了将 WGC 放置在两个预定义位置的后果。
本研究旨在量化 WGC 放置在两个位置时的性能降低：（1）平均偏心位置（ADL；戴巩膜镜的个体观察到的平均偏心位置）和（2）镜片的几何中心（GC）。
使用 36 例患有角膜扩张的常规巩膜镜佩戴者的去识别残余像差和镜片平移数据，在计算机上模拟 WGC 矫正。WGC 从眼睛特定的瞳孔位置向 ADL 和 GC 位置偏心。通过高阶均方根（HORMS）波前误差的变化（从对齐的、眼睛特定的瞳孔位置）、对数视觉斯特雷尔比（logVSX）的变化以及预测的对数最小可分辨视力（VA）的变化来评估这些失准的影响。
正如预期的那样，与对齐状态相比，HORMS 增加，logVSX 降低，预测的 VA 更差，在 ADL 和 GC 均如此（P<0.001）。36 只眼中的 34 只眼在 GC 处的残余 HORMS 更大，36 只眼中的 33 只眼在 GC 处的 logVSX 值更差。从临床角度来看，ADL 处的 36 只眼中有 19 只眼和 GC 处的 36 只眼中有 35 只眼的预测 VA 损失超过三字母。
将 WGC 放置在 ADL 或 GC 处，预计会导致超过一半的研究眼的 VA 明显下降，这表明简化适配过程的代价不值得。
