Worldwide geographical distribution of ophthalmology publications.

International peer-reviewed publications form the basis of evidence-based medicine and are one of the main indicators of ophthalmology research activity. This paper examines the origins of such articles in relation to geographical location, population demographics and economic research profiles. Publications from five ophthalmology journals over 5 years were analysed using the Medline/Pubmed search engine. Country of origin was ascertained based on the address of the corresponding author. Worldwide ophthalmology research output was analysed in relation to population demographics and research expenditure. In total, 7,754 articles from 67 countries from 2002 to 2006 were analysed. The overall number of articles published increased by over 29% during this period. The United States (US) produced the greatest number of articles. Singapore produced the most publications per 10(6) population. There was a relationship between gross domestic product (GDP) greater than $20,000 and population-adjusted output. The US followed by the United Kingdom and Japan were the greatest gross contributors. Population-adjusted figures revealed that Singapore, Iceland and Australia were the most prolific nations. There was a relationship between GDP and the top-ranked population-adjusted countries. The top 10 most productive population-adjusted countries spend relatively more on research and development than the top 10 gross contributors.