Severe visual loss by inhalation of methanol.

Purpose: To describe a clinical case of toxic optic neuropathy with severe visual loss caused by inhalation abuse of methanol products. Method: A 25-year-old male student was admitted to the emergency department with an acute bilateral visual loss and headaches, nausea, and cold sweats. A complete clinical and ophthalmologic examination was performed.

Results

On ophthalmic examination, visual acuity (VA) was light perception in the right eye (RE) and no light perception in the left eye (LE). Pupillary examinations demonstrated dilated, non-reactive pupils. An arterial blood gas analysis showed systemic metabolic acidosis with a pH of 7.23 and Gap anion elevated. Consequently, these results were enough to provide a substantial suspicion of methanol toxicity and start the treatment. 72 hours after, he confessed that he had been inhaling methanol-based solvent for eight years.

Conclusions

Methanol-induced toxicity can cause a non-reversible toxic optic neuropathy. Blood acidemia with Gap anion elevated and a suspicious fundus ophthalmic examination allows a fast diagnosis. A quick treatment based on dialysis, intravenous ethanol, sodium bicarbonate, vitamin B12, and intravenous methylprednisolone slows the secondary intoxication damages. We presented herein a procedure to identify and manage toxic optic neuropathy caused by methanol inhalation. Abbreviations: VA = Visual Acuity, RE = right eye, LE = left eye, OCT = Optical Coherence Tomography, RNFL = Retinal Nerve Fiber Layer, CT = computed tomography, MRI = magnetic resonance imaging, VEPs = visual evoked potentials.