2025 © Uva Clinical Anaesthesia and Intensive Care ISSN 2827-7198 / Keratitis: corneal inflammation September 4, 2025 2025 © Uva Clinical Anaesthesia and Intensive Care ISSN 2827-7198 / Keratitis: corneal inflammation 1 Keratitis: A Comprehensive Review of Etiology, Epidemiology, Pathophysiology, and Histopathology Indunil Karunarathna 1 , Palith Aluthge 1 , Keshali Senanayake 1 , Shani Jayasinghe 1 , Udara Sovis 1 , Supi Fernando 1 , Paw Umayangana 1 , Neha Perera 1 , Sena Gunathilake 1 , Kap De Alvis 1 , PNG Rodrigo 1 , Asok Jayawardana 1 , Cam Fernando 1 , USG Vidanagama 1 , UPN Ekanayake 1 , TMB Hapuarachchi 1 , Sasi Ranasinghe 1 , Sach Senanayaka 1 , Prasan Gunasena 1 , Kap Gunawardana 1 , Sam Rajapaksha 1 , Ban Rathnayak 1 , AN Thilak Warnakulasooriya 1 , Palinda Athulgama 1 , Mud Abeyek 1 , San Dius 1 , Ram Ranwala 1 , Sau Bandar 1 , Sanj Godage 1 , Suni Senadeera 1 , Jaga Wijepala 1 , 1. Ministry of Health / Teaching Hospital Badulla / Teaching Hospital Polonnaruwa / University of Colombo. 2025 © Uva Clinical Anaesthesia and Intensive Care ISSN 2827-7198 / Keratitis: corneal inflammation https://cmb.academia.edu/IndunilKarunarathna,, https://scholar.google.com/citations?user=knaeLaEAAAAJ&hl=en, https://www.adscientificindex.com/scientist/indunil- karunarathnai-karunarathna/6105403 , https://scholar.google.com/citations?user=C1PBnykAAAAJ&hl=en , Uva Clinical Research Lab https://www.researchgate.net/lab/Uva-Clinical- Research-Lab-UCRL-Indunil-Karunarathna , indkaru@gmail.com Abstract: Keratitis represents a broad spectrum of corneal inflammation with multifactorial etiology, ranging from infectious agents such as bacteria, fungi, viruses, and protozoa to non-infectious causes including immune-mediated and traumatic triggers. While the clinical diagnosis of keratitis is relatively straightforward due to its hallmark manifestations of ocular pain, photophobia, redness, and corneal opacity, the precise determination of etiology remains challenging. Early diagnostic differentiation is critical because mismanagement —particularly with the injudicious use of topical corticosteroids—may worsen the prognosis, especially in fungal and protozoal keratitis. The disease carries a significant global burden, particularly in developing nations where agricultural trauma is a major predisposing factor. Prognosis varies with the underlying cause; bacterial keratitis generally responds well to treatment, whereas fungal and Acanthamoeba keratitis are often protracted and refractory, with higher risks of corneal scarring and vision loss. Complications, including corneal perforation, toxic iridocyclitis, and sequelae such as phthisis bulbi, can have devastating outcomes. Preventive measures, patient education, and multidisciplinary collaboration between ophthalmologists, microbiologists, and rheumatologists play pivotal roles in improving patient safety and functional recovery. This review synthesizes the pathophysiological basis, differential diagnosis, complications, prognostic determinants, and modern therapeutic strategies in keratitis to provide a comprehensive guide for clinicians. Keywords: Keratitis; Corneal ulcer; Acanthamoeba; Fungal keratitis; Herpes simplex virus; Vision loss; Corneal scarring; Penetrating keratoplasty; Ophthalmic complications; Ocular trauma. Key Points Keratitis is multifactorial: infectious (bacterial, viral, fungal, protozoal) and non-infectious (trauma, immune- mediated). Differential diagnosis is complex—early Acanthamoeba and viral keratitis mimic each other; fungal keratitis often masquerades in chronic stages. Prognosis depends on etiology: bacterial ulcers resolve faster; fungal and Acanthamoeba keratitis are protracted with higher complication risks. Complications are vision-threatening: perforation, toxic iridocyclitis, secondary glaucoma, phthisis bulbi. Education and prevention matter: eye protection in agricultural workers, prophylaxis for recurrent HSV, and early medical intervention reduce morbidity. Team-based care improves outcomes: integration of microbiology for early pathogen identification and rheumatology for immune-modulated keratitis enhances patient safety.