Flüeler U R, Guyton D L
Department of Ophthalmology, Wilmer Ophthalmological Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
Surv Ophthalmol. 1995 Jul-Aug;40(1):45-50. doi: 10.1016/s0039-6257(95)80046-8.
An astigmatic dial viewed by a tilted retina will have only one line in focus, simulating astigmatic blur. We compare and contrast this optical situation to actual astigmatism. Photographs were taken of an astigmatic dial blurred with a cylindrical lens, and also of the same astigmatic dial tilted, simulating tilted retinal imagery. A model eye for retinoscopy practice was provided with a retina tilted 30 degrees and was retinoscoped repeatedly with and without added confounding cylinder by five skilled retinoscopists. Photographs of the astigmatically blurred and tilted astigmatic dials were similar but not identical, as expected. The model eye with tilted retina showed no astigmatism by retinoscopy in 14/15 measurements and 0.25 D of astigmatism in one measurement. When confounding cylinder was present, the retinoscopic measurement was always within 0.25 D of the added cylinder. The ocular imagery resulting from a tilted retina can simulate astigmatic blur, but this is actually due to a type of curvature of field. Only a minute area of the tilted retina is viewed during retinoscopy, so the tilt has essentially no influence on the retinoscopic reflex.
倾斜视网膜观察到的散光视标只有一条线清晰聚焦，模拟散光性模糊。我们将这种光学情况与实际散光进行比较和对比。拍摄了用柱面透镜模糊处理的散光视标照片，以及模拟倾斜视网膜成像的同一散光视标倾斜后的照片。为检影练习提供了一个视网膜倾斜30度的模型眼，由五位熟练的检影师在添加和不添加混淆柱镜的情况下反复进行检影。正如预期的那样，散光模糊视标和倾斜散光视标照片相似但并不完全相同。倾斜视网膜的模型眼在15次测量中有14次检影显示无散光，一次测量显示有0.25 D散光。当存在混淆柱镜时，检影测量值始终在添加柱镜值的0.25 D范围内。倾斜视网膜产生的眼内成像可模拟散光性模糊，但这实际上是由于一种场曲类型。检影时仅观察到倾斜视网膜的微小区域，因此倾斜对视标反射基本没有影响。
