Hydrogel-Based Ocular Drug Delivery Systems: A Bibliometric and Visualization Analysis of Research Trends and Hotspots (1991–2025)

Background: Ocular drug delivery is hindered by the eye’s complex anatomy and multiple physiological barriers. Because of their biocompatibility, biodegradability, and capacity to prolong drug retention, hydrogels have emerged as promising platforms for ocular drug delivery. This study provides a bibliometric and visual analysis of research on hydrogel-based ocular drug delivery from 1991 to 25 August 2025. Methods: Publications were retrieved from the Web of Science Core Collection and screened for relevance. CiteSpace, VOSviewer, and the Bibliometrix R package were used to analyze annual publication trends, contributions and collaborations among countries, institutions, and authors, core journals, and evolving research themes. Results: A total of 1354 publications (991 articles and 363 reviews) were included. Annual output increased markedly after 2007–2008, reflecting rapid growth in this field. China and the USA were the leading contributors, and the University of Florida was the most productive institution. Keyword co-occurrence, clustering, and burst analyses identified in situ hydrogels, tissue engineering applications, and anti-VEGF delivery as major research hotspots. Conclusions: This study maps the growth and diversification of hydrogel-based ocular drug delivery research, revealing a shift toward disease- and segment-specific applications, with controlled-release, stimuli-responsive systems, injectable hydrogels, and anti-VEGF as emerging research priorities.