congenital internal strabismus – onset in the first 6 months of life – usually not combined with obvious refractive abnormalities, no amblyopia if strabismus occurs alternately in both eyes, monocular strabismus can be combined with amblyopia – pseudo-abduction limitation – can be combined with congenital conditions such as hypermetropia, DVD, nystagmus, etc. Internal strabismus should first be investigated by dilating the pupil to rule out fundus disease or other structural abnormalities of the eye. Dilated eye examinations rule out obvious refractive abnormalities, although congenital internal strabismus generally has no obvious refractive abnormalities. Children who cooperate in strabismus testing and are binocularly equivalent are treated surgically as early as possible. In addition to restoring aesthetics, peripheral fusion is restored as much as possible.