Hammond Billy R, Buch John, Hacker Lauren, Cannon Jessica, Toubouti Youssef, Renzi-Hammond Lisa M
Vision Sciences Laboratory, Behavioral and Brain Sciences Program, Department of Psychology, The University of Georgia, United States.
Johnson and Johnson Vision Care, Inc., United States.
J Optom. 2020 Oct-Dec;13(4):227-234. doi: 10.1016/j.optom.2020.03.006. Epub 2020 Apr 21.
To assess the visual effects of wearing both an activated and an inactivated photochromic contact lens, with a direct comparison to a non-photochromic contact lens worn in the fellow eye. This study focused on the visual effects of scatter quantified as the minimum distance between two points of light, and the diameter of the halo and starbursts that surround a bright white point source.
60 subjects (aged 18-65 years) were measured in a contralateral design where lens type was randomly assigned, one type to each eye. During activated testing, all visual measures of both study lenses were made while each eye was illuminated by a violet (λ=365, half bandwidth 20nm) activator, which caused steady-state activation of the photochromic lens during the period of testing. Two-point thresholds were determined by measuring the minimum distance between two points of broadband xenon light. Glare geometry was measured using an aperture (∼4mm) that created a bright point source of light 45 inches from the plane of the eye. Between the point source and subject, a centering precision caliper was used to measure lateral spread of halos (diffusion around the source) and visual spokes. The head was stabilized using an adjustable head-rest assembly and the eye was aligned and monitored with a bore camera.
Compared to the non-photochromic lens, and based on the stimulus conditions used in these measurements, the activated and inactivated photochromic lens reduced the light spread using the two-point threshold technique by 32% and 19% respectively; the diameter of the halos were reduced by 44% and 16% respectively; and the spokes were narrowed by 39% and 20% respectively. Based on 95% confidence interval testing, these effects were all statistically significant (p<0.05).
These results are consistent with previous data showing that soft contact lenses with a photochromic additive can improve many aspects of visual function, consistent with their level or activation. Our past data focused on visual function under bright light conditions (e.g., glare disability, discomfort, photostress recovery and chromatic contrast) with an activated photochromic. In this study, we found differences even in the inactivated state, using less intense stimuli (10cd/m at the source). This suggests that the photochromic lens improves the effects of light scatter even at lower luminance.
评估佩戴激活态和非激活态光致变色隐形眼镜的视觉效果，并与对侧眼佩戴的非光致变色隐形眼镜进行直接比较。本研究重点关注以两点光之间的最小距离量化的散射视觉效果，以及围绕明亮白色点光源的光晕和星芒的直径。
采用对侧设计对60名受试者（年龄18 - 65岁）进行测量，随机分配镜片类型，每只眼睛佩戴一种类型。在激活测试期间，当每只眼睛被紫罗兰色（λ = 365，半带宽20nm）激活器照射时，对两种研究镜片进行所有视觉测量，该激活器在测试期间使光致变色镜片达到稳态激活。通过测量宽带氙灯光两点之间的最小距离来确定两点阈值。使用孔径（约4mm）测量眩光几何形状，该孔径在距眼睛平面45英寸处产生一个明亮的点光源。在点光源和受试者之间，使用定心精度卡尺测量光晕的横向扩展（光源周围的扩散）和视觉辐条。使用可调节的头枕组件稳定头部，并使用孔相机对准和监测眼睛。
与非光致变色镜片相比，基于这些测量中使用的刺激条件，激活态和非激活态光致变色镜片使用两点阈值技术分别使光扩散减少了32%和19%；光晕直径分别减少了44%和16%；辐条分别变窄了39%和20%。基于95%置信区间测试，这些效果均具有统计学意义（p < 0.05）。
这些结果与先前的数据一致，表明添加了光致变色添加剂的软性隐形眼镜可以改善视觉功能的许多方面，与其激活水平一致。我们过去的数据集中在激活态光致变色镜片在强光条件下的视觉功能（例如，眩光残疾、不适、光应激恢复和色对比度）。在本研究中，我们发现即使在非激活状态下，使用强度较低的刺激（光源处10cd/m）也存在差异。这表明光致变色镜片即使在较低亮度下也能改善光散射的效果。
