Outbreak of methanol-induced optic neuropathy in early COVID-19 era; effectiveness of erythropoietin and methylprednisolone therapy

Methanol Induced Optic Neuropathy: Molecular Mysteries, Public Health Perspective, Clinical Insights and Treatment Strategies

Methanol-induced optic neuropathy (MION) represents a critical public health issue, particularly prevalent in lower socioeconomic populations and regions with restricted alcohol access. MION, characterized by irreversible visual impairment, arises from the toxic metabolization of methanol into formaldehyde and formic acid, leading to mitochondrial oxidative phosphorylation inhibition, oxidative stress, and subsequent neurotoxicity. The pathogenesis involves axonal and glial cell degeneration within the optic nerve and potential retinal damage. Despite advancements in therapeutic interventions, a significant proportion of affected individuals endure persistent visual sequelae. The study comprehensively investigates the pathophysiology of MION, encompassing the absorption and metabolism of methanol, subsequent systemic effects, and ocular impacts. Histopathological changes, including alterations in retinal layers and proteins, Müller cell dysfunction, and visual symptoms, are meticulously examined to provide insights into the disease mechanism. Furthermore, preventive measures and public health perspectives are discussed to highlight the importance of awareness and intervention strategies. Therapeutic approaches, such as decontamination procedures, ethanol and fomepizole administration, hemodialysis, intravenous fluids, electrolyte balance management, nutritional therapy, corticosteroid therapy, and erythropoietin (EPO) treatment, are evaluated for their efficacy in managing MION. This comprehensive review underscores the need for increased awareness, improved diagnostic strategies, and more effective treatments to mitigate the impact of MION on global health.

Therapeutic role of erythropoietin in methanol induced optic neuropathy: a systematic review

PURPOSE

Despite various therapeutic attempts, an approved treatment for Methanol-induced optic neuropathy (MION), a sight-threatening disorder, is still lacking. Erythropoietin known as an erythropoietic cytokine, possesses various non-hematopoietic properties that make it a candidate for MION treatment. This systematic review aims to assess the potential therapeutic role of erythropoietin in MION.

METHOD

We systematically searched English and Persian databases including PubMed, Scopus, Embase, Web of Science, and Scientific Information Database (SID) as of July 2024. Two independent authors screened the articles based on their titles, abstracts, and full texts to finalize the included articles in this study. The selected articles underwent quality assessments via the Joanna Briggs Institute (JBI) checklists.

RESULTS

Out of 139 studies identified in the databases, 11 were finally included in the analysis. These studies encompassed 212 participants, with 192 receiving erythropoietin treatment. Visual acuity (VA) improved in 184 patients, with improvements ranging from no light perception to full vision recovery, or minor enhancements such as an improvement from 1.75 ± 0.72 to 1.32 ± 0.79 LogMAR. Only 8 patients showed no change or experienced deterioration. Additionally, 21 cases exhibited a reduction in retinal nerve fiber layer thickness, with one showing a reduction towards the normal range.

CONCLUSION

This review highlights erythropoietin's positive impact on VA in patients with MION. However, simultaneous use of erythropoietin and corticosteroids in studies without control groups complicates evaluating erythropoietin's independent efficacy. Future research should involve large, controlled trials to clarify erythropoietin's role and establish it as a standard treatment.

PROSPERO REGISTRATION NUMBER

CRD42023485772.

Sadaga N, Hadrawi M. Erythropoietin for the Treatment of Methanol Toxic Optic Neuropathy: Does It Really Work? A Case Series

Erythropoietin (EPO) has demonstrated neuroprotective properties and has been used in small case series to treat methanol optic neuropathy. This study aims to evaluate the effectiveness of EPO. This retrospective case series included data from patients diagnosed with methanol optic neuropathy between November 2022 and December 2023 from two centers in Jeddah, Saudi Arabia. Demographic information, time of consumption of methanol to EPO treatment, and other treatments administered were collected. Vision assessment was performed before and after EPO treatment. A total of 8 male patients were included, with an average age of 38.25 ± 7.15 years. The median duration of the follow-up was 66 days, ranging from 13 to 660 days. The means of vision in the logMAR of both eyes before EPO treatment was 1.98 ± 1.08, which changed to 1.87 ± 0.89 after EPO treatment. Patient's presenting vision before EPO treatment is a significant positive predictor for the vision after treatment with coefficient = 0.782 and 95% CI = 0.349, 0.936. Time to EPO treatment was not statistically significant in defining end vision. Treating methanol optic neuropathy is challenging and time sensitive. In this case series, EPO and adjuvant steroids showed variable effects on visual improvement. Although the vision improved after the treatment, these differences were not statistically significant. Repeat EPO did not give better outcomes. Long-term follow-up is needed to determine the overall impact of EPO treatment.