In this article by Vaajanen et al., two registers were analyzed in Finland, the first, the Finnish Register of Vision Impairment (VI), with entries based on clinical examinations by ophthalmologists. The past 40 years of data were analyzed in order to calculate incidence of reported vision impairment (<0.3 visual acuity) due to glaucoma, the 2nd most common cause of VI after age-related macular degeneration in the country. The second register, from the Social Insurance Institution of Finland, records those reimbursed for glaucoma medications, and this was accessed independently to provide data on numbers of treated glaucoma patients in Finland over a similar timeframe. The authors reassure me that both of these registers are highly representative of those vision impaired and those with treated glaucoma, respectively, evidenced by data from the latter closely reflecting self-reported glaucoma prevalence and measured visual acuity data from two national surveys in Finland in Yr 2000 and 2011.1
The authors report that incidence of reported VI in those with treated glaucoma has reduced by a third over 40 years, from 32/100,000 in the 1980's to 21/100,000 in the 2010-2019 decade, with no sex differences. The Olmsted County (Minnesota, USA) population-based study is one of the few other studies to have reported over such a long time period.2 This reported that the probability of glaucoma related blindness in at least one eye at 20 years had decreased from 26% for subjects diagnosed in 1965-1980 to 13% for those diagnosed in 1981-2000. A global meta-analysis of multiple cross-sectional studies has also recently reported a significant reduction in age-standardized prevalence of glaucoma blindness for the past 3 decades globally and in all world regions.3
Although it is to be welcomed that impact in terms of severity of VI appears to be reducing in Finland and globally, this is tempered by the increasing numbers of glaucoma patients on account of the ageing of our populations
This Finnish study reported that the proportion of overall VI that was classified as mild VI (defined as visual acuity <0.3 but ≥ 0.1) has increased in recent decades to approximately 50% suggesting better glaucoma care and earlier diagnosis, and this may be reflected in their finding that age of onset of reported VI had increased in more recent decades. It also highlighted higher incidence of reported VI among male than among female patients which may reflect later diagnosis among males. Despite the limitations of using registry- based data which the authors acknowledge, this report offers a fascinating insight into glaucoma's impact in a country which benefits from a very comprehensive registry system. Although it is to be welcomed that impact in terms of severity of VI appears to be reducing in Finland and globally, this is tempered by the increasing numbers of glaucoma patients on account of the ageing of our populations.