Instituto de Óptica (CSIC), Madrid, Spain.
School of Optometry, Indiana University, Bloomington, Indiana, USA.
Ophthalmic Physiol Opt. 2022 Sep;42(5):1074-1091. doi: 10.1111/opo.13008. Epub 2022 May 27.
Monocular polyplopia (ghost or multiple images) is a serious visual impediment for some people who report seeing two (diplopia), three (triplopia) or even more images. Polyplopia is expected to appear if the point spread function (PSF) has multiple intensity cores (a dense concentration of a large portion of the radiant flux contained in the PSF) relatively separated from each other, each of which contributes to a distinct image. We present a theory that assigns these multiple PSF cores to specific features of aberrated wavefronts, thereby accounting optically for the perceptual phenomenon of monocular polyplopia. The theory provides two major conclusions. First, the most likely event giving rise to multiple PSF cores is the presence of hyperbolic, or less probably elliptical, umbilic caustics (using the terminology of catastrophe optics). Second, those umbilic caustics formed on the retinal surface are associated with certain points of the wave aberration function, called cusps of Gauss, where the gradient of a curvature function vanishes. However, not all cusps of Gauss generate those umbilic caustics. We also provide necessary conditions for those cusps of Gauss to be fertile. To show the potential of this theoretical framework for understanding the nature and origin of polyplopia, we provide specific examples of ocular wave aberration functions that induce diplopia and triplopia. The polyplopia effects in these examples are illustrated by depicting the multi-core PSFs and the convolved retinal images for clinical letter charts, both through computer simulations and through experimental recording using an adaptive optics set-up. The number and location of cores in the PSF is thus a potentially useful metric for the existence and severity of polyplopia in spatial vision. These examples also help explain why physiological pupil constriction might reduce the incidence of ghosting and multiple images of daily objects that affect vision with dilated pupils. This mechanistic explanation suggests a possible role for optical phase-masking as a clinical treatment for polyplopia and ghosting.
单眼复视（重影或多个图像）是一些人严重的视觉障碍，他们报告看到两个（复视）、三个（三重视觉）甚至更多的图像。如果点扩展函数（PSF）具有多个强度核（PSF 中包含的大部分辐射通量的密集集中）彼此相对分离，则预计会出现复视，每个强度核都会贡献一个清晰的图像。我们提出了一种理论，将这些多个 PSF 核分配给像差波前的特定特征，从而在光学上解释单眼复视的感知现象。该理论提供了两个主要结论。首先，产生多个 PSF 核的最可能事件是存在双曲，或较少情况下是椭圆脐形焦散线（使用突变光学的术语）。其次，在视网膜表面形成的那些脐形焦散线与波前像差函数的某些点有关，称为高斯尖点，其中曲率函数的梯度为零。然而，并非所有的高斯尖点都会产生这些脐形焦散线。我们还提供了使这些高斯尖点具有生殖力的必要条件。为了展示该理论框架理解复视的性质和起源的潜力，我们提供了诱导复视和三重视觉的眼部波前像差函数的具体示例。通过计算机模拟和使用自适应光学设置进行实验记录，为临床字母图表描绘了多核 PSF 和卷积视网膜图像，显示了这些示例中的复视效果。PSF 中的核的数量和位置因此是空间视觉中复视存在和严重程度的潜在有用指标。这些示例还帮助解释了为什么生理瞳孔收缩可能会减少对扩张瞳孔视觉有影响的日常物体的重影和多个图像的出现。这种机制解释表明光学相位掩模可能在复视和重影的临床治疗中发挥作用。
