Biophotonics and Photodynamic Therapy: Emerging Optics-Based Treatments for Eye Conditions

Background: Ophthalmic medicine is increasingly leveraging the precision of light-based technologies for diagnosis and treatment. Biophotonics, the interaction of light with biological systems, and Photodynamic Therapy (PDT), a light-activated treatment, represent paradigm shifts in managing complex eye diseases. These provide targeted approaches with fewer adverse effects compared to conventional treatments. Aim: The aim is to synthesize current evidence and technological advances in the years between 2013 and 2025 about the use of biophotonics and PDT to treat a range of ocular pathologies, from AMD to corneal disorders and oncological pathologies. Methods: A narrative literature review was performed using PubMed, Scopus, and Web of Science. Search terms included "ophthalmic biophotonics," "photodynamic therapy," "verteporfin," "corneal cross-linking," "retinal imaging," and "light-guided therapy."  Results: The evidence confirms the established role of PDT in treating neovascular AMD and central serous chorioretinopathy. Significant refinements are noted toward the optimization of PDT parameters ("half-dose," "half-fluence") to enhance safety. Novel applications of PDT are emerging, such as in corneal neovascularization and ocular tumors. Simultaneously, biophotonic techniques, including two-photon microscopy and optogenetics, are entering the clinical arena from the research domain, providing unprecedented diagnostics at the cellular level and vision restoration strategies. Conclusion: Biophotonics and PDT represent the cornerstone technologies in current ophthalmology. Their evolution to more selective, personalized, and combination treatments promises an improvement in therapeutic outcomes and further extension of the frontiers of eye diseases that can be treated. Future integration with AI and nanotechnology will continue to cement their leading role in the revolution of ophthalmic care.