Near vision chart with fixed distance positioning rod

Abstract

The invention discloses a near vision chart with a fixed distance positioning rod. The near vision chart comprises a sighting target base plate, a positioning rod and a frontal plate, wherein an insertion tenon is arranged on a base part of the positioning rod; an insertion hole is formed on the sighting target base plate; the insertion tenon on the positioning rod is inserted into the insertion hole on the sighting target base plate; the frontal plate is connected to a tail end of the positioning rod; the thickness of the frontal plate is 10mm; the effective length of the positioning rod is 240-390mm. The invention has the advantages that: when the near vision chart with the fixed distance positioning rod is used for testing vision, the distance between an eye and the sighting target base plate is fixed, 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 fixed, so that the test result of the vision is accurate; the near vision chart with the fixed distance positioning rod is very suitable for families; and 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.

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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