Optical coherence tomography is highly sensitive in detecting prior optic neuritis

Objective To explore sensitivity of optical coherence tomography (OCT) in detecting prior unilateral optic neuritis. Methods This is a retrospective, observational clinical study of all patients who presented from January 1, 2014, to January 6, 2017, with unilateral optic neuritis and OCT available at least 3 months after the attack. We compared OCT retinal nerve fiber layer (RNFL) and ganglion cell inner plexiform layer (GCIPL) thicknesses between affected and unaffected contralateral eyes. We excluded patients with concomitant glaucoma or other optic neuropathies. Based on analysis of normal controls, thinning was considered significant if RNFL was at least 9 µm or GCIPL was at least 6 µm less in the affected eye compared to the unaffected eye. Results Fifty-one patients (18 male and 33 female) were included in the study. RNFL and GCIPL thicknesses were significantly lower in eyes with optic neuritis compared to unaffected eyes (p < 0.001). RNFL was thinner by ≥9 µm in 73% of optic neuritis eyes compared to the unaffected eye. GCIPL was thinner by ≥6 µm in 96% of optic neuritis eyes, which was more sensitive than using RNFL (p < 0.001). When using a threshold ≤1st percentile of age-matched controls, sensitivities were 37% for RNFL and 76% for GCIPL, each of which was lower than those calculated using the intereye difference as the threshold (p < 0.01). Conclusions OCT, especially with GCIPL analysis, is a highly sensitive modality in detecting prior optic neuritis, which is made more robust by using intereye differences to approximate change. Classification of evidence This study provides Class III evidence that OCT accurately identifies patients with prior unilateral optic neuritis.