Research on eye health 2000-2019: a global bibliometric analysis with a focus on equity

To summarise global peer-reviewed primary research on eye health published from 2000 to 2019.

We used the 'explode eye disease' function on MEDLINE to obtain all articles reporting primary research studies on eye health published between 1 January 2000 and 31 December 2019. We were intentionally broad and included population, clinical, animal and laboratory studies. We categorised the main eye condition of the paper from Medical Subject Headings (MeSH) terms, and the country of the study from the first country listed in the abstract (or if this was absent, the affiliation of the first author). A validated algorithm was used to assign gender to authors.

We included 158 697 publications from 178 countries. Across the period, annual research output increased globally (4.2% per annum, 5057 publications in 2000 to 10 875 in 2019) and in 20 of 21 regions. There was substantial geographical maldistribution, with research output ranging from 1.0 publication/million population in Central Sub-Saharan Africa to 165.8/million in Australasia; 70% of research identified was conducted in high-income countries (n=1 11 417). 42% of publications focused on one of the five leading causes of vision impairment. Of the 789 463 authorships assigned a gender, women held 33% of all (n=261 636/789 463), 36% of first (n=47 729/131 664) and 24% of last authorships (n=31 720/129 800). Women formed 50% of authorship teams when the last author was a woman (IQR 38-71%), compared with 20% of teams when the last author was a man (IQR 0-40%).

The annual research output doubled globally over the two decades, with a disproportionate output from high-income countries and slow progress towards gender parity. The main limitations of our study included the use of a single database, which may have led to an underestimation of all outputs, particularly from low- or middle-income countries.