Test for Strabismus (Heterotropia)

Rodolfo T. Rafael,MD

    Determine whether the patient has useful vision in each eye. Ask the patient to fixate on an object at the end of the room or at your penlight held about 13 inches (33 cm) away from him. First cover his left eye with your right hand. Watch the uncovered right eye to see if it moves to take up fixation. Uncover the left eye and allow him to look with both eyes. Then cover the right eye and watch the uncovered left to see if it moves to fixation. If there is fixation movement, the patient has heterotropia (strabismus, squint). To determine if the heterotropia is paralytic or nonparalytic, ask him to follow your penlight in the six cardinal directions of gaze (both eyes look to right, right and up, left and up, left, left and down, right and down). If the eyes move equally without restriction, the deviation is nonparalytic. If one overshoots and the other fails to look the entire distance in one or more directions, the deviation is paralytic. When fixation movements are absent in the cover-uncover test, try the alternate cover test. Cover the eyes alternately and watch the uncovered eye. If there is fixation movement, the eye has heterophoria.