toxic amblyopia

Last reviewed 01/2018

Nutritional amblyopia is defective vision secondary to poor diet - particularly, a deficiency of thiamine. Alcohol is a frequent finding on account of it's association with a poor nutritional state. In toxic amblyopia, agents such as lead, quinine, salicylates, cyanide intoxication due to tobacco, ethambutanol, rifampicin and methanol may be aetiologic factors.

Tobacco amblyopia is characterised by a central loss of vision for colours, in the order, green, green and red, and in extreme cases, white. Optic atrophy results in severe cases. In quinine amblyopia, the retinal vessels also become constricted and the peripheral vision is reduced. Methanol poisoning is accompanied by acidosis.

Adequate nutrition - with additional thiamine, folic acid and vitamin B12 may reverse nutritional amblyopia. Any toxic agent implicated should be removed.