Incidence of Leber hereditary optic neuropathy in 2019 in Japan: a second nationwide questionnaire survey.

Background: Leber hereditary optic neuropathy (LHON) is an acute or subacute optic neuropathy that mainly affects young males. The first nationwide epidemiological survey of LHON was conducted in 2014 in Japan, and LHON was officially designated as a rare intractable disease by the Japanese government in 2015. We conducted a second survey of the annual incidence of LHON in 2019, and estimated the total number of patients with LHON in Japan.

Results: A questionnaire was sent to 997 facilities accredited by the Japanese Ophthalmological Society and/or affiliated with the councilors of the Japanese Neuro-Ophthalmology Society. Responses were received from 791 facilities, with a response rate of 79%. Fifty-five newly diagnosed cases (49 males and 6 females) of LHON were reported from 35 institutions in 2019, with a median age of 28.5 for males and 49.5 years for females. The total number of newly diagnosed cases was calculated as 69 (62 were males and 7 were females, 95% confidence interval 55-83), and the total number of patients was estimated to be 2491 (95% confidence interval: 1996-2986), suggesting a prevalence of LHON in Japan of 1:50,000.

Conclusion: The incidence of LHON in 2019 was lower than the estimate in 2014, whereas its prevalence may be similar to that reported in other countries. The accurate estimation of the incidence and prevalence of patients with LHON requires prospective registration.