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本视力表是参照有关国际标准及缪天荣教授对数视力表原理设计而成,可测视力范围:五分视力记录值4.0～3.0;小数视力记录值0.1～0.01;视角值10～100′。本视力表的设计目的旨在解决低下视力无法统计及低下视力的增减值无从计算、比较的问题。设计原理:1.采用8个三划等长的E字形视标;2.以(?)的几何级数增率进行变距设计,变距范围从5米～0.5米,即实际检查距离比标准检查距离(5
This chart is based on the reference to the relevant international standards and Professor Miao Tianrong theory of logarithm of the logarithm designed, measurable range of visual acuity: five-point visual record of 4.0 to 3.0; fractional visual acuity recorded 0.1 to 0.01; perspective 10 ~ 100 ’. The purpose of this vision chart is designed to solve the low vision can not be counted and reduce the visual acuity of the increase or decrease can not calculate, compare the problem. Design principles: 1. The use of eight three-dimensional contour of the E-shaped visual target; 2. To (?) Geometric series of incremental design variable pitch, ranging from 5 meters to 0.5 meters, the actual inspection of the distance ratio Standard inspection distance (5