Baraldi P, Enoch J M, Raphael S
Int Ophthalmol. 1986 May;9(2-3):173-8. doi: 10.1007/BF00159846.
We have developed a new set of tests for evaluation of visual function through media opacities, based on vernier acuity measurements (hyperacuity). In this paper, results of one of these tests, the 'gap test', are compared in patients with posterior subcapsular (PSC) cataract versus nuclear cataract (NC). Patients with PSC cataract often report multiple images or significant 'star burst' effects. We hypothesized the presence of 'multi-prismatic' and/or high frequency spurious resolution phenomena due to PSC cataract characteristic substructure. We were able to minimize these effects by using a pinhole held close to the eye, a large (adapting) background field of white light superimposed on the vernier test targets, a low-pass spatial filter applied to the targets. When the particular problems associated with PSC cataract are not present or are adequately addressed and when patients are matched for visual acuity, the hyperacuity 'gap test' shows less functional effect due to the opacity for PSC cataract than NC in all the cases we have tested. These findings, moreover, indicate that visual acuity provides an insufficient description of the effects of intraocular scattering on image formation. The results emphasize the importance and the necessity of developing models that better clarify the specific effects of different types of ocular media opacities.
我们基于游标视力测量（超视力）开发了一套新的通过介质混浊评估视觉功能的测试方法。在本文中，对其中一项测试——“间隙测试”在后部囊下（PSC）白内障患者与核性白内障（NC）患者中的结果进行了比较。PSC白内障患者常报告出现多个图像或明显的“星芒”效应。我们推测由于PSC白内障特征性亚结构存在“多棱镜”和/或高频伪分辨率现象。通过使用靠近眼睛的针孔、叠加在游标测试目标上的大的（适应性）白色背景光场以及应用于目标的低通空间滤波器，我们能够将这些效应降至最低。当与PSC白内障相关的特定问题不存在或得到充分解决，且患者视力匹配时，在我们测试的所有病例中，超视力“间隙测试”显示PSC白内障混浊对功能的影响比NC小。此外，这些发现表明视力对眼内散射对图像形成的影响描述不足。结果强调了开发能更好阐明不同类型眼介质混浊具体影响的模型的重要性和必要性。
