Optical coherence tomography (OCT) findings in patients with optic tract syndrome

Abstract

Purpose To analyze retinal nerve fiber layer (RNFL) thickness in eyes with optic tract syndrome (OTS) by using optical coherence tomography (OCT) and to evaluate the capability of OCT to detect the characteristic pattern of RNFL loss. Methods Eight patients (4 males and 4 females) with optic tract syndrome were enrolled in this retrospective collection of medical records. Characteristics including age, sex, etiology of optic tract lesion, visual acuity, visual field defect type were recorded. The diagnosis of optic tract syndrome were made by clinical history and typical optic disc findings, visual field defect and neuro-imaging findings including brain MRI and/or CT. The average of RNFL thickness of optic disc, four quadrants, specific four o’clock meridians and related parameters were analyzed and compared between both eyes. Results The nasal segment average of RNFL thickness was significantly lower in contralateral eyes than that of ipsilateral eyes (37.5 ± 6.7 μm and 67.9 ± 10.3 μm respectively; p < 0.001). The average RNFL thickness and mean thickness of other three quadrants were not significantly different between both eyes. The ratio of superior maximum to nasal segment (Smax/Navg), superior maximum to temporal segment (Smax/Tavg) and inferior maximum to temporal segment (Imax/Tavg) of were significantly different between both eyes ( p < 0.001 in all comparisons). The RNFL thickness at nasal, temporal sectors of the contralateral and those at superior, inferior sectors of the ipsilateral eyes were significantly thinner than those of fellow eyes. Conclusion The RNFL thickness measured by OCT demonstrated a characteristic pattern of optic atrophies in OTS. The difference of nasal average, Smax/Navg, Smax/Tavg, Imax/Tavg values and specific radians between both eyes can provide useful information in the diagnosis of optic tract syndrome.