Evaluation of visual function and OCT parameters in ethambutol-induced optic neuropathy: a longitudinal study

Area of Science:

• Ophthalmology
• Neuroscience
• Toxicology

Background:

• Ethambutol is a key antibiotic for tuberculosis treatment.
• Ethambutol-related toxic optic neuropathy (EON) can impair vision.
• Understanding EON's structural and functional impact is crucial for patient management.

Purpose of the Study:

• To assess structural and visual functional changes in patients with ethambutol-related toxic optic neuropathy (EON).
• To identify predictors of visual recovery in EON.

Main Methods:

• Prospective study of 95 adults with EON and 100 controls.
• Evaluated visual acuity, color vision, contrast sensitivity, and visual fields.
• Utilized spectral domain optical coherence tomography (SD-OCT) for retinal nerve fiber layer (RNFL), papillomacular bundle (PMB), and macular ganglion cell-inner plexiform layer (mGC-IPL) thickness measurements.

Main Results:

• 52% of EON eyes showed visual improvement after drug cessation.
• RNFL and PMB thickness were comparable at baseline but thinned significantly by 6 months.
• GC-IPL thickness and GCL volume were significantly reduced at baseline and further deteriorated over time.
• GC-IPL thickness, GCL volume, and PMB thickness correlated negatively with final visual acuity.

Conclusions:

• Progressive structural damage in EON suggests potential irreversibility, despite some visual recovery.
• PMB thickness, GC-IPL thickness, and GCL volume are significant predictors of visual outcomes in EON.