The incidence of visual impairment due to retinitis pigmentosa has declined in Finland over the last 40 years.

Purpose: To study the changes in incidence, age at onset and severity of visual impairment (VI) due to retinitis pigmentosa (RP) in the Years 1980-2019, and the incidence and age at diagnosis of hereditary retinal dystrophy (HRD) diagnoses coded by ICD10 H35.5 in the Years 1998-2019 in Finland.

Methods: A total of 1606 persons with VI due to RP registered by the Finnish Register of Visual Impairment and total of 4291 HRD diagnoses registered by the Care Register of the Finnish Institute for Health and Welfare were included. VI was classified according to the Finnish national definitions derived from the WHO definitions. The significance of the changes in incidence and age at onset were tested with statistical tests (Kruskal-Wallis, Mann-Whitney U and Cochran-Armitage). Two-tailed p-value below 0.05 was considered significant.

Results: The incidence of VI due to RP has decreased from 0.96/100 000 in the 1980s to 0.55/100 000 in the 2010s (p 0.004). The age at onset of VI has increased from 41.6 to 50.3 years. The severity of VI has not changed. The incidence of HRD diagnoses has decreased from 3.66/100 000 in the 2000s to 2.86/100 000 in the 2010s (p 0.024). The age at diagnosis has risen in male patients from 42.1 to 44.5 years (p 0.024).

Conclusion: The VI caused by RP in Finland has decreased. It develops at an older age than in the past. We hypothesize that this trend may be attributed to informed decisions by visually impaired persons to refrain from having offspring to prevent the transmission of hereditary mutations. The severity of VI due to RP has remained relatively unchanged. The incidence of HRD diagnoses has decreased, and the diagnosis occurs at an older age among men.