Congenital Optic Tract Hypoplasia

During the assessment for ocular hypertension, a 67-year-old male was incidentally diagnosed with right incongruous homonymous hemianopia. Fundoscopy revealed bowtie atrophy of the right optic disc. Macular Optical Coherence Tomography analysis of the ganglion cell layer revealed thinning of the left hemi-retina in both eyes, corresponding to the observed visual field defect. Brain magnetic resonance imaging demonstrated complete atrophy of the left optic tract, with associated thinning on the left side of the chiasm and the right optic nerve. The patient also had a left-beating jerk nystagmus which he incidentally discovered at age 16. His past medical history, neuro-ophthalmological examination and ancillary tests led to the diagnosis of congenital hypoplasia of the optic tract. This extremely rare congenital malformation can remain unrecognized until late adulthood, as evidenced by this case.