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What are the standard eye charts?_Industry News_

by:Eugenia     2022-04-05
If you want to know if you have myopia, it is the easiest way to test with a visual acuity chart. There are many visual acuity charts, such as logarithmic visual acuity chart, point near visual acuity chart, M near visual acuity card and Jaeger. Each type of visual acuity chart has a different method of recording visual acuity. The logarithmic visual acuity chart uses 4.5, 5.0, etc. to record visual acuity, which is a recording method of the standard visual acuity chart. So which of the visual acuity charts belong to the standard visual acuity chart? 1. The logarithmic visual acuity chart is developed from the distance visual acuity chart. The myopia standard can be set as the E visual standard, the circular visual standard, the letter visual standard and the digital visual standard. The number of rows and the increase rate of the visual target are modeled on the logarithmic visual acuity chart. The common detection distance is 40cm, 30cm or 25cm. The elevation of the visual target is determined according to different detection distances, which is called the equivalent logarithmic myopia chart. 2. Click into the visual acuity chart The visual standard of the visual acuity chart is designed to read text. The visual standard value is represented by 'dotAt 1/72in, which is 0.353mm, the size of the visual standard is designed to be 11 lines from 16N to 1.6N, which are 16N, 13N, 10N, 8N, 6.6N, 5N, 4N, 3.3N, 2.5N, 2N, and 1.6 N, the standard detection distance is 40cm. 3. M Near Vision Card The visual standard of the M Reading Near Vision Card is a high-contrast reading text, divided into 10 sections. The visual standard value is expressed by a section coefficient, and the standard measurement distance is 40cm. The section coefficient values u200bu200bof the M reading vision card are divided into 4.0M, 2.5M, 2.0M, 1.6M, 1.2M, 1.0M, 0.8M, 0.6M, 0.5M, and 0.4M. 4. Jaeger eye chart Jaeger eye chart is a near vision chart developed from Snellen eye chart. It uses alphabetical symbols. There are 8 levels from JI to J8. The visual acuity increase rate is a harmonized level, that is, the elevation of JI is larger than J3. Three times, 8 times larger than J8. Since the logarithmic myopia chart became popular, the Jaeger eye chart has been rarely used.
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