Operation method: The examiner sits at a distance of one meter, facing the patient, the patient wears the trial frame, and the center of the frame circle should be placed at the center of the pupil of the eye being examined. The other side is covered with a black piece, and the patient's eyes are directed to the upper edge of the flat lens on the scope. Then the light source is directed into the pupil area of the patient, and the reflection of the pupil is peered behind the central hole of the mirror, and the mirror is turned slightly and slowly up and down or left and right, at which time the red and yellow or light yellow reflected light can be seen moving in the pupil area.