Optical coherence tomography findings in methanol toxicity

Area of Science:

• Ophthalmology
• Toxicology
• Neuroscience

Background:

• Methanol toxicity is a significant public health issue, particularly in developing countries, often resulting from consumption of adulterated alcoholic beverages.
• It can lead to severe visual impairment, making awareness of its toxic optic neuropathy crucial for retinal specialists.
• This report details a case of severe systemic methanol toxicity with notable retinal findings on optical coherence tomography (OCT).

Observation:

• A student presented with ataxia, respiratory distress, and loss of consciousness after consuming homemade alcohol.
• Initial laboratory results revealed severe metabolic acidosis (serum pH 6.79) and elevated methanol levels.
• Ocular examination showed bilateral central scotomas and visual field defects, despite normal retinal nerve fiber layer (RNFL) on OCT.

Findings:

• Ganglion cell layer (GCL) analysis on OCT revealed selective loss of nasal fibers in both eyes.
• Macular OCT demonstrated inner nuclear layer (INL) microcysts corresponding to the areas of GCL loss.
• These findings suggest preferential damage to the papillomacular bundle in methanol optic neuropathy.

Implications:

• The case illustrates the evolution of methanol toxicity, showing segmental GCL involvement with RNFL preservation.
• The presence of INL microcysts, reported here for the first time in methanol optic neuropathy, may be a non-specific indicator of papillomacular bundle damage.
• Understanding these specific retinal changes aids in diagnosing and managing methanol-induced visual impairment.