Following are the clinical features of Leber optic neuropathy except
Ans. is 'c' i.e., Males can transmit the disease Leber's Hereditary optic neuropathv Leber's hereditary optic neuropathy is characterized by sequential subacute optic neuropathy in males aged 11-30 years. The underlying genetic abnormality is a point mutation in mitochondria! DNA. Since mitochondrial DNA is exclusively derived from mother, males do not transmit the disease and the disease is transmitted by carrier females. It is characterizeed by bilateral, painless, subacute visual failure that develops during young adult life. Males are four to five times more likely than females to be affected. Affected individuals are usually entirely asymptomatic until they develop blurring affecting the central visual field of one eye; Similar symptoms appear in the other eye an average of two to three months late. In about 25% of cases, visual loss is bilateral at onset. On examination, patients generally have bilateral impairments of visual acuity. There is centrocecal scotoma that begins nasal to the blind spot and extends to involve fixation of both sides of the veical meridian. Pupillary reactions are often normal. Ophthalmoscopic examination shows fundus abnormalities in acute phase like swelling of the disc, peripapillary retinal telangiectasia, but characteristically there is no leak from the optic disc during fluorescein angiography. Later in atrophic phase, disc becomes atrophic and pale.
Seen in the 2nd or 3rd decade of life
It is a example of gradual painless visual loss
Males can transmit the disease
No leak of dye is observed in fluorescein angiography