The onset of the disease in the first 6 months of life is usually not combined with obvious refractive abnormalities, and there is no amblyopia if both eyes alternate with strabismus; monocular strabismus can be combined with amblyopia. Due to the crossed visual field of both eyes, there can be pseudo-extension limitation. Congenital internal strabismus can be combined with hypermetropia, DVD, and nystagmus. First, we should determine whether there is monocular amblyopia and the ability to gaze Ciliary muscle paralytic agent dilated pupil examination Fundus examination to exclude congenital abnormalities Eye movement examination to determine whether there is hypotropia, DVD, nystagmus, etc. Treatment: Exclude monocular amblyopia, if there is monocular amblyopia, amblyopia treatment to binocular vision balance is required. If congenital internal strabismus is treated surgically, the timing of surgery should be 1-2 years old. The surgical design should be considered accordingly for those with hypermetropia and DVD. After surgery, the 10 trigeminal microstrabismus should be preserved to facilitate the establishment of peripheral fusion and coarse stereo vision. Case 1: Internal strabismus at birth, alternate gaze in both eyes, +25. at 1 year of age, +60△ on trigeminal examination; +40. at 3 years of age, +90△ on trigeminal examination. Surgery: 5 mm posterior migration of the internal rectus muscle in both eyes. 10 days after surgery: both eyes were basically orthotropic, alternately covering the inner – middle.