Some patients are curious and ask: Can a doctor check for strabismus in less than a minute? The answer is a resounding yes. The following is the method that doctors use to quickly diagnose strabismus. 1. Corneal light reflection method: Let the person being examined look at the light 33cm in front of him/her, if the corneal reflection point is located in the center of the pupil of both eyes, the eye is orthotropic, i.e. there is no strabismus. If the corneal light reflection appears in the center of the pupil of one eye, but the other eye is at the pupillary margin, the skew is about 10 to 15 degrees; at the corneal margin, the skew is about 45 degrees. 2, alternate masking method: let the examined person look at the light of 33cm, then use the palm of the hand to repeatedly alternate between the left and right eyes to block the line of sight. Observe whether there is any rotation of the uncovered eye at the moment of alternate covering. This method is very sensitive and can detect occult strabismus or strabismus of 2 degrees or more. 3, extraocular muscle function check method: let the examined person look at the light of 33cm, and the light moves to the left, right, upper left, upper right, lower left, lower right directions respectively, to determine whether there is a problem with a certain muscle of one eye by observing whether the movement of both eyes is uncoordinated. Therefore, for a well-trained and skilled ophthalmologist, the basic skill of detecting strabismus within one minute has long been practiced in years of work. Three seemingly simple tests can detect: (1) the presence or absence of strabismus; (2) whether the strabismus is occult or dominant; (3) the approximate degree of strabismus; (4) whether the eye movements are uncoordinated; (5) which of the 12 extraocular muscles in both eyes are paralyzed or restricted as a direct result of the uncoordinated eye movements; (6) which muscle movement abnormalities are primary and which movement abnormalities are secondary?