LY-22C DISTANCE VISUAL ACUITY CHART
The LY-22C Distance Visual Acuity Chart offers a variety of optotypes to meet standard optometry needs. It includes optotypes such as Tumbling E, Landolt C, Number chart, Snellen chart, red/green bar, Worth-4 dot chart, Astigmatic Fan Dial, Cross cylinder, and more.
LED background light 5 meters testing distance
Astigmatism Optotype
When the astigmatism lines are uniform in direction and thickness, it confirms that the examined eye's astigmatism has been fully corrected or that there is no astigmatism present.
Red and Green Optotype
If the green area appears clear and bright, it indicates that the correction for myopia is higher than that for hyperopia.
If the red area appears clear and bright, it suggests that the correction for myopia is insufficient and the correction for hyperopia is too high. The goal is to achieve clarity in both the red and green areas.
Worth 4-dot Optotype
The test subject wears red-green glasses, with the left eye seeing green and the right eye seeing red. The eyes are fixed on the target, and the patient is asked to report the number of lights and their colors.
2 red lights: Only the right eye is used, and the left eye is suppressed.
3 green lights: Only the left eye is used, and the right eye is suppressed.
5 lights (3 red and 2 green): Diplopia (double vision).
4 lights (1 red, 2 green, 1 mixed green): Normal binocular vision.
Cross Cylinder Optotype
The test subject should be able to observe all dots clearly and uniformly. If some black dots appear in different shades with rough outlines, it indicates the possibility of astigmatism.
The following types are optional:
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