Abstract:
Background: Optic neuropathies represent a significant cause of irreversible visual impairment worldwide. In low-resource settings, a substantial proportion is attributable to preventable and treatable nutritional deficiencies and environmental toxins. Conditions like Vitamin B12 deficiency, alcohol-related optic neuropathy, and cassava associated cyanide toxicity are often overlooked, leading to delayed diagnosis and permanent vision loss.
Objective: To synthesize current evidence on the epidemiology, clinical presentation, etiological factors, and management challenges of nutritional and toxic optic neuropathies, with a focus on applicability in low-resource settings.
Methods: A systematic search of PubMed, African Journals Online (AJOL), WHO Global Index Medicus, and Google Scholar was conducted up to September 2025, following PRISMA 2020 guidelines. Studies reporting on nutritional, toxic, or deficiency-related optic neuropathies in low- and middle-income countries (LMICs) were included. Two reviewers independently screened, extracted, and appraised data.
Results: Out of 42 identified records, 14 met the eligibility criteria. The review identified three primary etiologies: nutritional deficiencies (particularly Vitamin B12, Thiamine, and Folate), chronic alcohol misuse, and dietary cyanide exposure from improperly processed cassava. Clinical presentation is typically bilateral, progressive, painless visual loss with central or cecco-central scotomas. Studies from Sub-Saharan Africa report diagnostic delays averaging 6-12 months. Management is challenged by limited access to diagnostic tests (e.g., serum B12 assays), high cost of parenteral supplements, and lack of public awareness. A study from Nigeria found that over 60% of patients with nutritional optic neuropathy presented with visual acuity worse than 6/60.
Conclusion: Nutritional and toxic optic neuropathies remain a significant yet preventable cause of blindness in low-resource settings. A multifaceted approach is urgently needed, encompassing public health education on safe food preparation and balanced nutrition, capacity building for early diagnosis at the primary care level, and the development of cost-effective treatment protocols. Integrating management of these conditions into existing national nutrition and non-communicable disease programs could mitigate their visual burden.
