A young man with blurring of vision in right eye, followed by left eye after 3 months, showing disc hyperemia, edema, circumpapillary telangiectasia with normal pupillary response with centrocecal scotoma on perimetry, the cause is -

It is a type of hereditary optic neuritis which primarily affects males around the age of 20 years. It is transmitted by the female carriers. The condition is characterised by progressive visual failure. The fundus is initially normal or in the acute stage disc may be mildly hyperaemic with telangiectatic microangiopathy. Eventually bilateral primary optic atrophy ensues. Ref:AK Khurana 4thE pg 296.