1. Skewed eye position. Sometimes it is inappropriate for parents to discover it, but it is discovered by people around them. On the contrary, some parents consider the pseudo-internal obliquity as the true internal obliquity. Simple methods: photos of different periods, light reflection method, internal strabismus, external strabismus. 2. Amblyopia is formed by strabismic eyes, but those who can alternate gaze should not form amblyopia. 3. Prefer to close one eye in the sun. Avoid diplopia. 4. Ptosis, such as vertical strabismus, can be accompanied by true or pseudo ptosis. 5. Upward eye drift: e.g. DVD. 6. Nystagmus, e.g. congenital internal strabismus. 7. Vicarious cephalic position: face, head and neck. 8. Ocular slanting neck. 9. Diplopia. Such as paralytic strabismus, acute common internal strabismus.