|OPTIC NERVE HEAD HYPOPLASIA
SIGNS AND SYMPTOMS
If the condition is unilateral, a relative afferent pupillary defect may be noted. Other dysfunctions of the afferent system, such as diminished color vision, red desaturation and brightness perception will likewise be present. Visual field defects may also be elicited but vary considerably-altitudinal loss, central and cecocentral scotomas, and other field defects have been documented. In addition, up to 50 percent of patients manifest a constant strabismus, most often esotropia.
Examination reveals a smaller-than-expected optic nerve, with the
vasculature appearing large relative to the disc. If unilateral, there is a notable size
difference in the nerve heads. A circumpapillary ring of white or yellowish scleral tissue
is typically evident ("double-ring sign"). The normally bright reflex from the
nerve fiber layer is diminished. A review of the patient's history may reveal associated
brain disorders (e.g., absence of the septum pellucidum, pituitary dysfunction,
porencephaly) and/or gestational disease, as well as a history of maldeveloped growth.
Many disorders have been implicated in this disorder, including
gestational diabetes, maternal infection by cytomegalovirus, syphilis, rubella, fetal
alcohol syndrome and other drug use by the mother while pregnant. ONH hypoplasia may be
part of larger clinical syndromes such as septo-optic dysplasia, which is marked by short
stature, congenital nystagmus and a hypoplastic disc. The majority of patients, however,
have no associated systemic abnormalities.
In addition, many clinicians photograph the posterior pole of the affected eye and measure the disc-macula/disc-disc (DM/DD) ratio; this allows them to compare the horizontal diameter of the nerve head to the distance between the fovea and the center of the nerve. In a normal eye, the DM/DD measures between 2:1 and 3.2:1. Ratios greater than this suggest hypoplasia.
In uncomplicated unilateral cases, manage the condition through patient
education and protective eyewear. If the history or examination indicates any associated
neurological manifestations, refer the patient for studies to rule out forebrain disease.
Studies may include physical and neurologic evaluation, neuroimaging and endocrinologic
assessment. In more profound cases where both eyes are affected, consider visual
Other reports in this section
Eyelids & Eyelashes | Conjunctiva & Sclera | Cornea
Uvea | Vitreous & Retina | Optic Nerve & Brain | Oculosystemic Disease
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