Tutt R, Bradley A, Begley C, Thibos L N
School of Optometry, Indiana University, Bloomington, Indiana.
Invest Ophthalmol Vis Sci. 2000 Dec;41(13):4117-23.
The purpose of this study was to examine the optical and visual impact of tear break-up.
Optical quality of the eye was assessed during periods of nonblinking by quantifying vessel contrast in the fundus image and by monitoring the psychophysical contrast sensitivity and the spatial distribution of tear thickness changes by retroillumination. All measures were obtained from three eyes either with or without a soft contact lens.
A noticeable decrease in retinal vessel contrast and contrast sensitivity were observed soon after a blink. Both of these measures of optical quality of the eye showed a similar pattern of image degradation both with and without a soft contact lens. Although trial-to-trial variability was considerable, sample means show that image contrast in the low spatial frequency range can drop to between 20% and 40% of initial values after 60 seconds of nonblinking. Retroillumination of the tear film showed local intensity fluctuations that progressively spread across the pupil with increasing time after the blink.
Optical aberrations created by tear break-up contribute to the decline in image quality observed objectively and psychophysically. The decline in image quality that accompanies tear break-up may be a direct cause of the blurry vision complaints commonly encountered in dry-eye patients.
本研究旨在探讨泪膜破裂的光学和视觉影响。
通过量化眼底图像中的血管对比度以及通过视网膜反光法监测心理物理学对比度敏感度和泪液厚度变化的空间分布，在不眨眼期间评估眼睛的光学质量。所有测量均取自三只佩戴或未佩戴软性隐形眼镜的眼睛。
眨眼后不久，观察到视网膜血管对比度和对比度敏感度明显下降。这两种眼睛光学质量的测量方法在佩戴和未佩戴软性隐形眼镜时均显示出相似的图像退化模式。尽管每次试验之间的变异性很大，但样本均值表明，在不眨眼60秒后，低空间频率范围内的图像对比度可降至初始值的20%至40%之间。泪膜的视网膜反光显示局部强度波动，随着眨眼后时间的增加，这种波动逐渐扩散到整个瞳孔。
泪膜破裂产生的光学像差导致了客观和心理物理学上观察到的图像质量下降。泪膜破裂伴随的图像质量下降可能是干眼症患者常见的视力模糊症状的直接原因。
