Corneal infections, also known as infectious keratitis, are serious eye conditions that occur when bacteria, viruses, fungi, or parasites invade the cornea—the clear, dome-shaped surface at the front of the eye. When these infections lead to tissue breakdown, they form corneal ulcers, which are open sores on the corneal surface. Corneal infections are considered ophthalmic emergencies because they can progress rapidly and lead to permanent vision loss if not treated promptly and appropriately.

The cornea plays a critical role in focusing light and maintaining clear vision. Any disruption to its structure or transparency can significantly impair visual function. Corneal infections often develop when the natural protective barriers of the eye are compromised. Common risk factors include contact lens misuse or poor hygiene, eye trauma, foreign bodies, dry eye disease, eyelid abnormalities, prolonged steroid eye drop use, previous eye surgery, and systemic conditions such as diabetes or immune suppression.

Different organisms cause different types of corneal infections. Bacterial keratitis is the most common and can progress rapidly, often associated with contact lens wear. Viral keratitis, particularly caused by herpes simplex virus, may recur and lead to corneal scarring. Fungal keratitis is more common in agricultural settings and follows trauma with plant material. Parasitic infections, such as Acanthamoeba keratitis, are rare but severe and often linked to improper contact lens care.

Symptoms of corneal infection are typically severe and include intense eye pain, redness, blurred vision, excessive tearing or discharge, light sensitivity, and the sensation of a foreign body in the eye. As ulcers form, a visible white or gray spot may appear on the cornea. Vision can deteriorate quickly, emphasizing the need for urgent evaluation.

Diagnosis involves a detailed eye examination using slit-lamp biomicroscopy. Corneal scrapings may be taken for microbiological testing to identify the causative organism and guide targeted therapy. Awareness of the patient’s history, including contact lens use and recent trauma, is crucial for accurate diagnosis.

Treatment depends on the underlying cause and severity of the infection. Intensive antimicrobial eye drops are initiated promptly, often requiring frequent dosing. Severe cases may need hospitalization for close monitoring. In advanced infections, complications such as corneal scarring, thinning, perforation, or secondary glaucoma may occur. Surgical interventions, including therapeutic corneal transplantation, may be required in sight-threatening cases.

Early diagnosis and aggressive treatment are vital to preserving vision. With timely care, many corneal infections can be successfully treated, although some patients may experience residual visual impairment requiring further rehabilitation.