Ocular Suppression Development at Age 12 Years

BACKGROUND: The patient experienced idiopathic increased intracranial pressure (pseudotumor cerebri syndrome) leading to an acquired, constant left exotropia at age 12 years. She had diplopia for about 2 months which resolved due to apparent suppression of the left eye. The patient has maintained the suppression without developing amblyopia through her current age of 17 years despite a stable large left exotropia, optic atrophy, and visual field defect. SIGNIFICANCE: The case is unusual because suppression has been assumed to develop only prior to age 10 years. BACKGROUND AND PURPOSE: Ocular suppression is an active neuroplastic process and is presumably limited to a sensitive period in childhood. It occurs when there is a difference in image clarity between the two eyes. The two most common causes are clinically significant anisometropia and strabismus. The strabismus may be monocular and constant, alternating and constant, or intermittent. The presence of suppression in anisometropia or constant monocular strabismus often leads to monocular amblyopia. The literature contains extensive animal, laboratory, and clinical evidence on the sensitive period of amblyopia, its causes, and its remediation. It is well established that amblyopia develops prior to about age 7 years, can recur up to about age 10 years, but does not develop, recur, or regress after age 12 years. Generally, response to amblyopia treatment is most robust during the sensitive period, but it is well documented that successful treatment is possible through the teen years and even adulthood. Few reports exist on suppression without amblyopia and most are based on clinical experience. von Noorden and Campos state: “As with other sensorial adaptations, such as amblyopia and anomalous retinal correspondence (ARC), the ability to suppress is limited to the immature visual system, that is, it develops only in children. Although no comparative studies exist, it is our clinical impression that the sensitive period during which suppression may develop ends after the age of 8 or 9 years”. The present paper reports an interesting case of an apparent onset of suppression at age 12 years in a patient with acquired, constant, unilateral strabismus secondary to idiopathic increased intracranial pressure.