视力表的历史、现状与发展趋势

The Past, Present and Future of Visual Acuity Charts

视觉是人类最重要的感觉之一。视锐度反映了视觉系统辨别空间细节的能力, 是临床实践中最常用的视功能评估指标。视力表是使用最广的视锐度测量工具。笔者回顾了国内外视力表的发展历程, 简述了早期糖尿病视网膜病变治疗研究视力表和标准对数视力表的设计原理和计分规则。由于传统视力表自身的精度限制, 其在视力普查和儿童青少年近视防控工作中的局限性也日益凸显, 电子视力表代替传统视力表正逐渐成为趋势。笔者分析了当前不同电子视力表的硬件特性、软件算法逻辑和测量结果, 发现显示屏的分辨率和尺寸、程序的测量和计分规则等多种参数设置的不统一可能会造成不同设备测量视力的结果不具有可比性。研发规范化的新型电子视力表势在必行。

Vision is one of the most important human senses.Visual acuity,usually measured with acuity charts,quantifies the spatial resolution of the visual system,and is the most commonly used functional vision measure in clinical practice.Precise evaluation of visual acuity is of great importance for clinical and occupational health screening.In this paper,we briefly review the history of visual acuity charts,including the design principles and scoring rules of two of the most popular acuity charts,the Early Treatment of Diabetic Retinopathy Study(ETDRS)chart and the Standard Logarithmic Visual Acuity chart.Computerized visual acuity tests have emerged in recent years because of the inherent limitations of acuity charts,including low precision and large learning effects.We analyzed the hardware requirements,algorithms and performances of a range of computerized tests and found that the differences in parameter settings and test protocols made it impossible to compare acuity scores across different computerized tests.Therefore,there is an urgent need to standardize computerized visual acuity tests.