Worldwide ophthalmological research production 2000-2020, with special focus on the Nordic contribution

Abstract

Purpose: To explore the trends in worldwide ophthalmic research production over a 21-year period in relation to journals, contributing countries and dominating topics with special focus on the Nordic region.

Methods: Articles published between 2000 and 2020 in 20 top-ranked ophthalmology journals were included. Number of articles and impact points were measured per country for each year. The most frequently occurring keywords were calculated worldwide and for the top five contributing countries and the Nordic countries. Trends were explored using linear regression.

Results: The analysis included 65 220 articles. Linear regression showed an increase with 56 articles per year (β = 56.3, R² = 0.72, p-value < 0.01). The United States published the most articles, comprising 35% of the worldwide total, followed by the United Kingdom (9%) and Japan (7%). Population-adjusted productivity revealed that Iceland was the most prolific country with 10 articles per million inhabitants/year. Singapore was second and Denmark third with corresponding numbers of nine and seven. Analysing regional trends, Asia had the largest increase in yearly number of articles (β = 29.1, R² = 0.89, p-value < 0.01). The strongest positive trend was observed in China (β = 15.7, R² = 0.94, p-value < 0.01). The Nordic countries contributed with 3.6% of worldwide ophthalmological papers. Among these, Denmark was the only country with a significant positive trend in impact points per million inhabitants per year (β = 0.6, R² = 0.54, p-value < 0.01). The most frequently occurring eye disease within the whole time frame was myopia (5.8%) followed by macular degeneration (5.4%) and glaucoma (5.3%). Linear regression showed a significant increase in the proportion of articles about diabetic retinopathy (β = 0.2%, R² = 0.88, p-value < 0.01) a significant decrease in the proportion in articles about cataract (β = -0.1%, R² = 0.70, p-value < 0.01) and myopia (β = -0.1%, R² = 0.67, p-value < 0.01).

Conclusions: The worldwide ophthalmic research productivity has maintained a growing trend from 2000 to 2020. While North America and Europe are the major contributors, the scientific activity in Asia and especially China is growing impressively. With the current progress, Asia is forecast to outweigh Europe in 2025 and North America in 2033. Diabetic retinopathy was the most common eye disease in ophthalmologic papers in 2020, and also the topic with the strongest positive trend during 2000-2020.

Keywords: bibliometrics; journal impact factor; ophthalmology; publication productivity.

Fig. 1

World trends for articles, number of authors, references, and impact factor for 20 top‐ranked ophthalmological journals 2000–2020 with linear regression. [Colour figure can be viewed at wileyonlinelibrary.com]

Fig. 2

Trends in number of ophthalmological articles in worldwide regions and from top countries in the three most productive regions. [Colour figure can be viewed at wileyonlinelibrary.com]

Fig. 3

Trends in ophthalmological impact factor points for the Nordic countries 2000–2020. (Iceland is intentionally excluded due to high variance of this measure caused by a small population. Impact points were calculated for the given journal's mean impact factor for the whole time frame.) [Colour figure can be viewed at wileyonlinelibrary.com]

Fig. 4

Trends in global occurrence of the five most common ‘eye disease’ MeSH terms within the ophthalmological literature. [Colour figure can be viewed at wileyonlinelibrary.com]