1. The subject's head must be placed upright, blinking less, and eye adjustment should be relaxed as much as possible.

2. Each eye should generally be measured no less than 3 times.

3. During the measurement process, the display screen displays the words "E" or "RR", indicating that the credibility of the measurement data is less than 70% (usually caused by irregular astigmatism, cataracts, or blinking of the tested eye).

4. When the word "AAA" is displayed, it cannot be measured due to the movement of the tested eye position or the small pupils; The display of "OOO" or "OUT" indicates that the refractive index of the tested eye exceeds the measurement range.

5. The results provided by the computer optometry machine are not suitable for direct optometry, and must be reviewed before optometry can be performed.

6. Always keep the instrument clean and maintain it regularly. If any faults are found, repair them promptly and regularly recheck the accuracy of the instrument.