Global, regional and national patterns in ROP research up to the pre-COVID-19 era: A systematic bibliometric review between 1950 to 2020

Retinopathy of prematurity (ROP) is a leading cause of preventable childhood blindness, predominantly affecting preterm infants. Global disparities in neonatal care and research capacity influence the volume and visibility of scientific production devoted to ROP across regions. This systematic bibliometric review aimed to characterize global, regional, and national patterns of ROP research published between 1950 and 2020, including temporal trends, geographic distribution, thematic focus, and citation impact. A systematic search of PubMed, Scopus, Web of Science, and SciELO identified 4,932 eligible articles. Most publications originated from the Region of the Americas (Pan American Health Organization, PAHO; 44.2%), the European Region (EURO; 28.0%), and the Western Pacific Region (WPRO; 16.0%). High-income countries accounted for 73.4% of the total output, whereas lower-middle- and low-income countries were markedly underrepresented. The most frequent research themes were risk/protective factors (25.0%) and treatment and outcomes (23.5%), while studies addressing surveillance and public health policies were scarce (6.3%). Scientific output increased markedly after the 1980s, with particularly rapid growth in recent decades in the Western Pacific and South-East Asia Regions. Citation analysis revealed substantial regional inequalities, with publications from high-income regions accounting for the majority of global citations and higher per-article impact. Overall, ROP research remains highly concentrated in high-income settings, reflecting persistent global disparities in scientific production and visibility. Strengthening research capacity and output in underrepresented regions is essential to promote more equitable evidence generation and to support informed decision-making in global eye health.