Role of stem cells in ocular diseases: Progress and challenges

Ocular diseases, including corneal disease, glaucoma, age-related macular degeneration (AMD), diabetic retinopathy, and retinopathy of prematurity, can significantly impair vision and reduce quality of life. Because degenerated cells in these diseases are unable to regenerate, treatments for these conditions have limited efficacy. Stem cell therapies are revolutionizing the treatment of degenerative eye conditions, enabling structural and functional restoration through mechanisms such as cell replacement and paracrine signaling. This review examines advances in stem cell therapy for ocular diseases, from preclinical studies to early clinical trials, focusing on various types of stem cells, including embryonic stem cells, induced pluripotent stem cells (iPSCs), and mesenchymal stem cells. Significant progress has been made with iPSC-derived retinal pigment epithelial cell transplantation in AMD treatment, showing cell survival in trials, and with mesenchymal stem cells for corneal repair through anti-inflammatory effects. Challenges remain, such as controlling differentiation to prevent tumorigenesis, managing immune rejection, and ensuring manufacturing processes that comply with Good Manufacturing Practice standards. By integrating mechanistic insights with translational strategies, this review outlines pathways to optimize stem cell therapies for previously intractable ocular diseases.