hypertropia. vertical strabismus before and after surgery. human eyes healthy and with upward gaze position. double

hypertropia strabismus eye upward vertical squint amblyopia movement vision deviation ophthalmology double eyeball human disorder optometric iris pupil type anatomy muscle extraocular health convergent crossed heterotropia condition dysfunction farsightedness diverge misaligned diagnosis infographic symptom tropia drift position diplopia misalignment binocular gaze comparison patient medical therapy surgery before after