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

Background: 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.

Methods: 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.

Results: 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.

Conclusions: 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.