What is TEON?

Tanzanian Endemic Optic Neuropathy (TEON) causes irreversible vision loss in young people, resulting in significant disability and huge educational and economic implications. The condition, which is centred around the city of Dar es Salaam in East Africa, affects up to 2.4% of 10-39 year olds (40,000 people). Despite being a relatively common disease, the cause of TEON is still frustratingly unclear.

TEON is a bilateral optic neuropathy of subacute, progressive onset with best corrected visual acuities of 6/9 or worse in both eyes, alongside an acquired colour vision deficiency, in the presence of eventual temporal optic disc pallor or with initial optic disc hyperaemia. Associated features in some patients with TEON include hearing loss and peripheral neuropathy.