Otero Carles, Aldaba Mikel, Martínez-Navarro Beatriz, Pujol Jaume
Davalor Research Centre, Polytechnic University of Catalonia, Terrassa, Spain.
Centre for Sensors, Instruments and Systems Development (CD6), Polytechnic University of Catalonia, Terrassa, Spain.
Clin Exp Optom. 2017 Nov;100(6):649-655. doi: 10.1111/cxo.12534. Epub 2017 Mar 21.
The aim was to analyse the effect of peripheral depth cues on accommodation in Badal optometers.
Monocular refractions at 0.17 and 5.00 D of accommodative stimulus were measured with the PowerRef II autorefractor (Plusoptix Inc., Atlanta, Georgia, USA). Subjects looked (randomly) at four different scenes, one real scene comprising familiar objects at different depth planes (Real) and three virtual scenes comprising different two-dimensional pictures seen through a Badal lens. The first image consisted of a photograph of the real scene taken in conditions that closely mimic a healthy standard human eye performance (out-of-focus [OoF] blur); the second image was the same photograph rendered with a depth of focus to infinity (OoF sharpness); and finally the third image consisted of a fixation target and a even white surrounding (White). In all cases the field of view was 25.0° and the fixation target was a Maltese cross subtending to two degrees.
Twenty-eight right eyes from healthy young subjects were measured. The achieved statistical power was 0.9. At 5.00 D of accommodative stimulus, the repeated measures analysis of variance was statistically significant (p < 0.05) and the corresponding Bonferroni post hoc tests showed the following mean accommodative response differences and standard deviation (p-value) between the real and the virtual scenes: real-white =-0.66 ± 0.92 D (p < 0.01); real-OoF sharpness = -0.43 ± 0.88 D (p = 0.07); real-OoF blur =-0.25 ± 0.93 D (p = 0.89).
A stimulus poor in depth cues inaccurately stimulates accommodation in Badal optometers; however, accommodation can be significantly improved in the same Badal optometer, when displaying a realistic image rich in peripheral depth cues, even though these peripheral cues (also referred to as retinal blur cues) are shown in the same plane as the fixation target. These results have important implications in stereoscopic virtual reality systems that fail to represent appropriately retinal blur.
目的是分析周边深度线索对巴德尔验光仪调节功能的影响。
使用PowerRef II自动验光仪（美国佐治亚州亚特兰大市Plusoptix公司）测量0.17 D和5.00 D调节刺激下的单眼屈光度数。受试者（随机）注视四个不同场景，一个真实场景包含处于不同深度平面的熟悉物体（真实场景），以及三个虚拟场景，这些虚拟场景是通过巴德尔透镜看到的不同二维图片。第一张图像是在紧密模拟健康标准人眼表现（离焦[OoF]模糊）的条件下拍摄的真实场景照片；第二张图像是将同一张照片渲染为无限远的焦深（OoF清晰度）；最后第三张图像由一个注视目标和均匀的白色背景（白色）组成。在所有情况下，视野为25.0°，注视目标是一个张角为2度的马耳他十字。
对28名健康年轻受试者的右眼进行了测量。统计效能达到0.9。在5.00 D调节刺激下，重复测量方差分析具有统计学意义（p < 0.05），相应的Bonferroni事后检验显示了真实场景和虚拟场景之间的以下平均调节反应差异及标准差（p值）：真实场景 - 白色背景 = -0.66 ± 0.92 D（p < 0.01）；真实场景 - OoF清晰度 = -0.43 ± 0.88 D（p = 0.07）；真实场景 - OoF模糊 = -0.25 ± 0.93 D（p = 0.89）。
深度线索匮乏的刺激会不准确地刺激巴德尔验光仪的调节功能；然而，在同一台巴德尔验光仪中，当显示富含周边深度线索的逼真图像时，调节功能可得到显著改善，即便这些周边线索（也称为视网膜模糊线索）与注视目标处于同一平面。这些结果对未能恰当呈现视网膜模糊的立体虚拟现实系统具有重要意义。
