PurposeTo report the incidence and severity of reported visual impairment (VI) due to glaucoma and the changes in them during the past 40 years in Finland.MethodsA register‐based study, in which the data were collected from the Finnish Register of Visual Impairment between 1980 and 2019. These data included 5819 visually impaired glaucoma patients, of which 61% were female. Visual impairment (VI) was classified according to the Finnish national definitions. The number of treated glaucoma patients in Finland was calculated using glaucoma medication reimbursement data available between 1986 and 2019 from the Social Insurance Institution of Finland registers.ResultsThe incidence of reported VI due to glaucoma per 100 000 persons had increased from 2.3 in the 1980s to 3.4 in the 2010s. During the same time period, the incidence of reported VI per 10 000 treated glaucoma patients had decreased from 32 in the 1980s to 21 in the 2010s. Primary open‐angle glaucoma (45%) was the main subtype for reported VI due to glaucoma. During the 40 years, the proportion of mild VI and the age at the onset of reported VI had increased.ConclusionThe incidence of reported VI due to glaucoma has increased during the 40 years, but the risk of treated glaucoma patients becoming visually impaired has decreased. Visual impairment (VI) also occurs at an older age. This is likely due to the earlier diagnoses and improved therapy. To prevent the unfavourable development of VI due to glaucoma among the ageing population in the future, all attempts need to be made to improve glaucoma care.