The principle of strabismus surgery is to balance the eye position of the two eyes so that the two eyes look in the same direction and no strabismus occurs. The same is true for internal strabismus, i.e., weaken the internal rectus muscle, which is responsible for turning the eye inward, and strengthen the external rectus muscle, which is responsible for turning the eye outward, so that the power of turning inward is weakened and the power of turning outward is strengthened, thus correcting internal strabismus. The same has special strabismus such as upward and downward strabismus, eye upward strabismus will weaken the eye downward strabismus muscle, weaken the upward force, so that the eye will no longer appear upward floating situation, if there is a downward strabismus, can weaken the lower straight muscle, the lower force weakened the eye will naturally upward, by changing the muscle strength to correct strabismus.