Use of diffusing filters for artificially reducing visual acuity when testing equipment and procedures
Use of diffusing filters for artificially reducing visual acuity when testing equipment and procedures
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DOI：
10.1007/s10633-019-09715-5
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发表时间：
2020-02-01
影响因子：
1.4
通讯作者：
Struebin, Isabell
中科院分区：
文献类型：
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作者：
Heinrich, Sven P.;Struebin, Isabell
目的在评估眼科设备和程序时，例如用于视觉电生理学的眼科设备和程序，通常需要在视力降低的情况下进行测试。对有实际视力障碍的人这样做有一些缺点，例如相当大的招募工作，特别是当目标是特定的敏锐度范围时，以及对损害的实际感知特征几乎没有控制，这些特征通常不是完全了解的。在视力正常的观察者眼前放置正屈光度或模糊滤镜的镜片有望为这个问题提供一个简单的解决方案。然而，离焦会导致相当大的虚假分辨率，而且以前的研究表明，常用的邦格特封堵器并不是达到这一目的的最佳选择。因此，本研究审查了许多其他选择，并就其对敏锐度和对比敏感度的影响测试了一系列滤镜，目的是确定主要降低敏感度而大多不影响对比敏感度的滤镜。方法首先，我们筛选了几种可能有用的过滤器。然后使用弗莱堡视力和对比度测试来测量视力和对比敏感度，使用三个滤光片(Llightit LSD 0.5度和1度，以及Lee 420)的子集，并与标称视力等级为0.1的邦格特遮盖器进行比较。对滤光片对棋盘翻转VEP的影响也进行了定性比较。结果使用两种Llightit滤镜，受试者之间的敏锐度变异性相对较小，至少在0.5度版本中，对比敏感度的相对影响很小。Lee滤光片和Bangerter封堵器导致了更多的变异性，与对敏感度的影响相比，对比敏感度相对较大地降低。对比Llightit 0.5度和1度滤镜，视力下降与物理刺激退化不成正比。对VEP反应的影响与心理物理数据一致。结论具有高斯光扩散分布的Llightit滤光片是人工降低视力的一种很好的选择。
Purpose When evaluating ophthalmological devices and procedures, for instance those for visual electrophysiology, it is often desirable to perform tests with reduced acuity. Doing this with individuals with actual visual impairments has a number of disadvantages, such as considerable recruitment efforts, especially when a specific acuity range is targeted, and little control about the actual perceptual characteristics of the impairment, which are normally not fully known. Lenses with positive diopters or blurring filters that are placed in front of the eyes of visually normal observers promise a simple solution to the problem. However, defocus results in considerable spurious resolution, and previous studies suggest that the frequently used Bangerter occluders are not optimal for the purpose. The present study therefore reviews a number of other options and tests a selection of filters with respect to their effect on acuity and contrast sensitivity with the aim of identifying filters that primarily degrade acuity while mostly sparing contrast sensitivity. Methods First, we screened several filters for potential usefulness. The Freiburg Acuity and Contrast Test was then used to measure visual acuity and contrast sensitivity with a subset of three filters (Luminit LSD 0.5 degrees and 1 degrees, and LEE 420) and, for comparison, with a Bangerter occluder with a nominal acuity grade of 0.1. A qualitative comparison of the filters' effect on the checkerboard-reversal VEP was also performed. Results With both Luminit filters, variability in acuity across participants was relatively small, and at least with the 0.5 degrees version, contrast sensitivity was relativity little affected. The LEE filter and the Bangerter occluder resulted in more variability and, compared to the effect on acuity, a relatively strong reduction in contrast sensitivity. Comparing the Luminit 0.5 degrees and 1 degrees filters, the reduction of acuity was not proportional to physical stimulus degradation. The effect on VEP responses was consistent with the psychophysical data. Conclusions The Luminit filters, which have a Gaussian light diffusion profile, appear to be a good choice for artificial reduction of acuity.