1 Inspection Purpose

First, determine whether the subject has myopia and hyperopia. Second, whether to measure the diopter of corrective glasses worn for myopia and hyperopia.

2 Inspection Principle (Color Difference Principle)

After passing through the prism, white light will form seven different colors of light, namely red, orange, yellow, green, blue, indigo and purple (the wavelength is arranged from large to small, and the frequency is arranged from small to large). Light of different colors has different refractive power due to different wavelengths and frequencies. Among them, blue violet light has high frequency, small wavelength and strong bending force, while red orange light has low frequency, long wave and weak bending force. Green light has high frequency, small wavelength and strong refractive power. It focuses first, red light has low frequency, long wave, weak bending power and then focuses.

3 Inspection Method (When Astigmatism Is Completely Corrected)

a. Check the right eye first, then the left eye.

b. First use objective examination and preliminary correction.

c. Fog optometry makes the examined eye in a relaxed state for examination.

d. Find the best corrected visual acuity with maximum orthography through fog Optometry (the lowest degree for myopia and the highest degree for hyperopia).

e. Project the red and green visual markers on the line with the best vision. Let the examined eye see the green visual markers first, then the red visual markers, and then compare them from red to green (see Fig. 3 and 4).

f. If the red eye mark is relatively clear, it indicates that it is a state of mild myopia, and an appropriate negative ball mirror should be added in front of your eyes.

g. If the green mark is relatively clear, it indicates that it is in a state of mild hyperopia, and an appropriate spherical mirror should be added in front of your eyes.

h. If the red and green visual indicators are as clear, it means that the degree of the spherical mirror is basically accurate at this time.

4 Precautions

a. The subject shall be initially measured, and the fog optometry shall be applied to make the subject relax and adjust, and then the red and green visual mark shall be used to further measure the preliminary test results.

b. First look at the green sign, then the red sign, and then from red to green (pay attention to the specific inspection details of more than 0.8).

c. If the subject has astigmatism or visual function is inhibited, it should be noted that even if the clarity of red and green visual markers is applied, it can not be well judged, or even difficult to judge.