Spectral-domain optical coherence tomography detects optic atrophy due to optic tract syndrome

Unilateral injury of the optic tract leads to asymmetrical optic atrophy in both eyes derived from the crossing of the nerve fibers at the chiasm. This report demonstrates unique imaging appearances of optic atrophy due to this uncommon condition detected by spectral-domain optical coherence tomography (SD-OCT). Cirrus and RTVue measurements were performed in four cases of optic tract syndrome. Circumpapillary retinal nerve fiber layer (cpRNFL) thickness was obtained from both instruments and ganglion cell complex (GCC) integrity was obtained from RTVue. The presumable reduction rates of quadrant cpRNFL thickness were calculated from the published normative database and compared between eyes with temporal hemianopia and those with nasal hemianopia. Both devices showed significant reduction of cpRNFL thickness, but did not have statistical difference in the reduction rates at temporal or nasal quadrant cpRNFL between contralateral and ipsilateral eyes to the lesion. Color-coded maps helped to visualize the unique pattern of cpRNFL and GCC thinning. SD-OCT can be used as a diagnostic tool for the optic tract syndrome.