General Medical Information

Strabismus

Jean Edwards Holt

Most of the practice of pediatric ophthalmology centers on the study of strabismus (failure of the two eyes to look at the same object) and amblyopia, an important preventable cause of vision loss. Strabismus is misalignment of the two eyes so that only one eye is directed at the specific object of regard. General ocular inspection may reveal gross deviation of one eye. The corneal light reflex allows an estimation of the amount of the deviation. The cover test can help detect almost every case of strabismus. A small amount of phoria is present among most patients with normal eyes and should not be cause for alarm.

All newborns should be examined for gross alignment of the eyes. Up to 3 to 4 months of age, children often have uncoordinated eye movements and can temporarily manifest actual strabismus. An ophthalmologist should be consulted if occasional deviations persist beyond this age. Infants with constant deviations should be referred at any age as soon as possible. The determination, by examination or history, that a deviation is intermittent is an important prognostic sign. Normal binocular vision can develop only if there is precise coordination of the two eyes. If the mental object of regard is seen by one eye and another object seen by its fellow, the brain suppresses the accessory image to avoid diplopia, thereby turning off the input from the deviating eye. If the eyes are straight at least part of the time (intermittent strabismus) or if the deviation alternates (first one eye assumes fixation and then the other), there is a chance for full development of visual potential.