Correlation of retinal nerve fiber layer thickness (RNFL) and arterial blood gas profile with visual outcome in methanol induced optic neuropathy: a retrospective analysis with 12- month follow-up
Alireza Attar1 *
- poostchi ophthalmology research center, department of ophthalmology, school of medicine, shiraz university of medical sciences, shiraz, Iran
Abstract: Methanol-induced optic neuropathy (MTON) poses a serious threat with notable mortality and enduring visual complications. This study aimed to uncover the correlation between paraclinical findings, imaging modalities, and visual prognosis in acute methanol poisoning survivors. The objective was to contribute to the understanding of determinants for chronic visual changes, assess treatment efficacy, and predict visual loss.
Methods: Conducted as a prospective longitudinal cohort study during a mass methanol poisoning outbreak, 61 patients were included, and ethical principles were rigorously followed. The study spanned from March 2018 to April 2019, utilizing patient records from Ali Asghar Hospital in Shiraz. The treatment protocol involved interventions for acid-base and electrolyte control, hemodialysis, ethanol administration, and pharmaceuticals. Follow-up examinations occurred 12 months after discharge, including ophthalmologic exams and advanced imaging tools.
Results: Over the 12-month follow-up, retinal nerve fiber layer thickness (RNFLT) exhibited significant reductions in all regions, with the superior region experiencing the most pronounced loss. Arterial blood pH on admission displayed strong negative correlations with primary RNFLT, while serum bicarbonate and anion gap showed varied associations. Visual acuity, assessed by LogMAR, demonstrated improvement, with 90.2% of patients experiencing recovery. However, 9.8% faced persistent visual challenges.
Conclusion: This study provides crucial insights into the visual complications of methanol poisoning, emphasizing the association between metabolic acidosis and enduring visual impairment. The decline in RNFLT, particularly in the superior region, underscores the vulnerability of optic nerve axons. While the majority exhibited visual recovery, ongoing monitoring is imperative for those facing persistent challenges. The study contributes to effective intervention strategies and aids in predicting long-term visual outcomes in MTON survivors.
