Congenital Absence of the Optic Chiasm

Congenital absence of the optic chiasm or achiasma is a rare condition. Only a few cases have been reported in the literature. We report on a child with early onset nystagmus. Magnetic resonance imaging demonstrated absence of the optic chiasm with normal optic nerves and optic tracts. There were no other midline abnormalities, migration anomalies, space-occupying lesions, nor destructive processes. The child had an associated partial growth hormone deficiency. Early onset nystagmus may have many causes and congenital absence of the optic chiasm is very rare, but it should be included in the differential diagnosis of early onset nystagmus. Brain imaging is indicated when an abnormality of the visual pathways is suspected.