The bacterial species causing keratitis are the following: The systemic conditions predisposing to bacterial keratitis are diabetes mellitus, malnourishment, connective tissue or autoimmune pathologies, Steven-Johnson syndrome (SJS), ocular mucous membrane pemphigoid (OMMP), atopic dermatitis, xerophthalmia, blepharoconjunctivitis, 5th and 7th cranial nerve palsy, graft versus host disease, immunosuppression (AIDS) and chronic alcoholism. The various local factors are dry eyes, corneal suture-related infection, abnormalities of eyelid anatomy and function, trichiasis, blepharitis, chronic dacryocystitis, ectropion, entropion conjunctivitis, lagophthalmos neurotrophic keratopathy, recurrent corneal erosions, epithelial defect, secondary bacterial keratitis after viral keratitis, bullous keratopathy. Varied ocular surface diseases, either local or systemic, can also result in bacterial keratitis. The various extrinsic causes implicated are trauma, foreign body injury, chemical, mechanical and thermal injuries, insect fall, previous ocular and eyelid surgery, immunosuppression, drug-induced with corticosteroids and NSAID’s and substance abuse. The various factors which cause bacterial keratitis are contact lens (CL) overnight wear, overwear, inadequate cleaning of contact lens, rinsing the contact lens in tap water, contamination, lack of CL hygiene, bandage contact lenses, CL sharing, swimming with contact lenses, CL solution contamination, and CL induced trauma. Ĭontact lens use is one of the major causes of bacterial keratitis. When these barriers are disrupted, it may result in bacterial keratitis. The main barriers of microbial infection are anatomical barriers in the form of the bony orbital rim, eyelids, intact conjunctival and corneal epithelium, mechanical barriers like tear film mucus layer and lacrimal system, and antimicrobial barriers like tear film constituents IgA, complement components, lactoferrin, lysozymes and conjunctiva associated lymphoid tissue (CALT). With rapid advances in clinical diagnosis, growing research in molecular laboratory investigation, and targeted antimicrobial therapy, the visual morbidity has reduced to a decent extent, but it remains a significant cause of sight-threatening keratitis in underdeveloped and rural areas globally. The diagnosis rests on clinical and microbiological evaluation. The past few decades have seen a rapid increase in contact lens users globally, resulting in an increase in bacterial keratitis proportionately. When anatomical, mechanical and antimicrobial barriers of microbial keratitis are breached, it invites vision-threatening keratitis. The cornea can be invaded by various microorganisms like viruses, fungi, protozoa, and bacteria, but bacteria are most concerning due to rapidly progressive vision-threatening keratitis with irreversible visual sequelae. It can present as insidious progressive ulceration or rapidly deteriorating suppurative infection of any part of corneal tissue. It can be an acute, chronic, or transient infectious process of the cornea with a variable predilection for topographical, anatomical, or geographical domains of the cornea. This activity aims to give deeper insight into etiology, risk factors, epidemiology, clinical presentation, microbiological and histopathological analysis, treatment, complication, differential diagnosis, and prognosis of bacterial keratitis.īacterial keratitis or corneal ulcer is an infection of the corneal tissue caused by varied bacterial species. Rapidly progressive cases unresponsive to medical treatment require therapeutic keratoplasty. Antibacterials are the mainstay of treatment and adjuvant in the form of cycloplegics, antiglaucoma medications, and oral anti-inflammatory drugs. A meticulous slit lamp clinical examination, corneal scraping with smearing, and culture are mandated to reach a conclusive diagnosis. Bacterial keratitis is commonly associated with risk factors that disturb the corneal epithelial integrity. If untreated can lead to progressive tissue destruction, corneal perforation, or extension of infection to adjacent tissue. In some cases, there is rapidly progressive stromal inflammation.
Bacterial keratitis or corneal ulcer is a common sight-threatening ocular corneal pathology.
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