Optical Coherence Tomography Parameters and Optimal Cut-off Values for Predicting Visual Prognosis in Ethambutol-Induced Optic Neuropathy.

Abstract

The objective of this study was to evaluate the prognostic value of optical coherence tomography (OCT) parameters in patients with ethambutol-induced optic neuropathy (EON) and establish their optimal cut-off values for predicting visual acuity outcomes. A retrospective cross-sectional study was conducted on 64 eyes of 32 patients with EON who underwent OCT. Peripapillary retinal nerve fiber layer (pRNFL) and macular ganglion cell-inner plexiform layer (mGCIPL) thickness were measured using Cirrus high-definition OCT (HD-OCT) within 3 months after EON diagnosis. Visual acuity of patients was recorded and analyzed at the first visit, the 1-year visit, and the latest visit. Prognostic capacities of OCT parameters for visual prognosis were evaluated and their optimal cut-off values for predicting final visual acuity were established. Increased pRNFL thickness was significantly associated with better visual acuity at 1 year postdiagnosis and the latest visit. A significant association was established between increased pRNFL thickness and a higher rate of recovery to visual acuity >20/25 at 1 year postdiagnosis. Receiver-operating characteristic curves identified ideal cut-off values for OCT parameters as follows: pRNFL thickness of 83 μm (sensitivity 100%, specificity 48.3%) and mGCIPL thickness of 74 μm (sensitivity 100%, specificity 83.3%) for visual acuity >20/25 at 1 year, mGCIPL thickness of 61 μm (sensitivity 85.7%, specificity 71.4%) for visual acuity >20/40 at 1 year, with corresponding AUCs exceeding 0.7. Both pRNFL and mGCIPL thickness possess potential values for predicting visual outcomes in patients with EON. Future research should continue to explore the utility of OCT parameters in EON prognosis.