Amblyopia (lazy eye) can be caused by a strabism or by a refractive defect like myopia, hyperopia and astygmatism. Other factors can also play a role like some familial predisposition or birth prematurity. Indeed, this last group presents more easily refractive anomalies or strabism.
In strabism, the eyes can be convergent or divergent or deviated up or down. The most frequent form of strabism is the congenital strabism with the eyes squinted to the interior (esotropia). When one or both eyes are deviated to the interior, the child develops a lazy eye (amblyopia). In this case, it is necessary to perform an ophthalmologic examination to measure the ocular deviation and the refractive anomaly. In case of a refractive anomaly, it is necessary to prescribe glasses. The eye deviation and the stimulation of the lazy eye are effectuated covering the best eye. This could be necessary during several months or even years. After occlusion, strabism surgery should be performed to correct the deviation of both eyes to align them in a parallel way.
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