Near vision chart with distance positioning screw rod

Abstract

The invention discloses a near vision chart with a distance positioning screw rod. The near vision chart comprises a sighting target base plate, a threaded rod, a threaded sleeve and a frontal plate, wherein a base part of the threaded rod is fixedly connected with the sighting target base plate; the threaded sleeve is screwed on the threaded rod; and the frontal plate is connected to a tail end of the threaded sleeve. When the test distance is 250mm, the threaded sleeve is screwed to the bottom of the threaded rod; when the test distance is 400mm, the threaded sleeve is screwed out of the threaded rod till a scale line of the screw rod; when the near vision chart with the distance positioning screw rod is used for testing vision, the two test distances can be selected, and the forehead of a testee is adhered to the frontal plate; the distance between the frontal plate and the sighting target base plate is preset, so that the test result of the vision is accurate; the near vision chart with the distance positioning screw rod is very suitable for families; the vision of a child (a student) can be tested at any time, so that near vision can be discovered in time and treated or rectified in time; and the near vision chart with the distance positioning screw rod has a screw rod structure and the test distance can be regulated from 250mm to 400mm at random.

Description

technical field [0001] The invention relates to a near vision chart. Background technique [0002] The existing near vision chart generally specifies a detection distance of 250 mm or 400 mm when testing vision. Unlike a distance vision chart, the detection distance is 5000 mm or 5 meters, and the distance difference is dozens of times when testing vision. Millimeters do not affect the accuracy of judging vision. However, the detection distance of the near vision chart differs by tens of millimeters, and the detection results are quite different. How to control the distance between the human eye and the eye chart at a standard distance is a problem that needs to be solved. Contents of the invention [0003] The purpose of the present invention is to solve the problem that the detection distance specified by the existing near vision chart is 250 millimeters or 400 millimeters when detecting eyesight. Unlike the distance vision chart, the detection distance is 5000 millime...

AI Technical Summary

Problems solved by technology

[0002] The existing near vision chart generally specifies a detection distance of 250 mm or 400 mm when testing eyesight. Unlike the distance vision chart, the detection distance is 5000 mm or 5 meters away, and the distance difference is dozens of times when testing vision. mm does not affect the accuracy of judging vision

However, the detection distance of the near vision chart differs by tens of millimeters, and the detection results are quite different.

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