Toluene Related Toxic Optic Neuropathy

Abstract

Toxic optic neuropathy presenting as bilateral painless visual loss causing central or caecocentral scotoma has a wide differential diagnosis. In this report, we present a rare cause of toxic optic neuropathy presenting as almost indistinct optic disc margins in both eyes in a 30-year old man with blurred vision and difficulty in walking and in writing with a history of adhesive glue sniffing. Caecocentral scotomas in the visual fields; increased total error scores on Farnsworth-Munsell (FM) 100 Hue testing; P 100 reduced amplitude in the pattern visually evoked potentials; and N 95 reduced amplitude in the pattern electroretinogram associated with normal serum electrolytes and vitamin levels suggested acute toxic optic neuropathy related to toluene. Upon cessation of toluene use, the caecocentral scotomas almost disappeared, total error scores in the FM 100 Hue test decreased and visual acuity improved.

Drugs of abuse and ocular effects

“…127 Many affected patients are chronic users of inhalants and started consuming this substance during childhood, because of its ease of access. 128 The use of inhalants is higher in some First Nations communities. 129 Inhalants are lipophilic substances and cause neurotoxicity because of their affinity for the lipid-rich central nervous system.…”

“…129 Inhalants are lipophilic substances and cause neurotoxicity because of their affinity for the lipid-rich central nervous system. 128,[130][131][132][133] This group of substances is commonly reported to induce visual hallucinations, nystagmus horizontal or pendular, diplopia, blurry vision, [134][135][136][137] as well as acute or chronic toxic optic neuropathy. Occasional reports, with no proposed mechanism of pathophysiology, include combined third, fifth and sixth cranial nerve palsy, 138 bilateral internuclear ophthalmoplegia, 139 toxic maculopathy 140 and optic neuritis.…”