That red, painful eye might be keratitis, a serious inflammation of your cornea.

Health · Published 3 October 2026 Swipe more like this →

In short: Keratitis is the inflammation of the cornea, the clear tissue covering your pupil and iris. While minor injuries can trigger it, infectious forms caused by bacteria, viruses, or parasites can lead to permanent vision loss. Understanding the risks, especially for contact lens wearers, is vital for protecting your sight.

Keratitis manifests through symptoms like redness, intense pain, light sensitivity, and blurred vision. The condition is broadly categorized into infectious and noninfectious types. Noninfectious keratitis often stems from minor trauma, such as a foreign object in the eye or the prolonged use of contact lenses. Infectious keratitis, however, is driven by pathogens including bacteria like Staphylococcus and Pseudomonas, fungi, and viruses such as herpes simplex or herpes zoster. These microorganisms can thrive in contact lens cases, particularly when hygiene is poor or lenses are worn while swimming.

The diagnostic process typically involves a clinical examination, though specialists may use microbiological cultures to identify specific pathogens. Treatment is highly dependent on the underlying cause. Bacterial infections generally require antibiotic eye drops, while fungal or viral cases necessitate specific antifungal or antiviral therapies. In some instances, providers may use steroid eye drops to manage swelling after an infection has cleared, though their use is nuanced; for example, applying steroids to a dendritic ulcer caused by herpes simplex can significantly worsen the condition, potentially leading to geographic-shaped ulcers.

Complications can be severe, ranging from chronic inflammation and corneal scarring to the formation of corneal ulcers and blindness. Contact lens wearers are at a notably higher risk, with studies indicating that bacteria are the most common causative agent in this group. Prevention strategies focus on rigorous lens hygiene, such as replacing cases every three to six months and avoiding swimming while wearing lenses. For those with viral keratitis, frequent hand washing and avoiding contact with eye areas during outbreaks are essential. If medication fails and scarring occurs, a cornea transplant may be required.

General information, not professional advice. Spotted an error? Flag the card or see corrections and complaints.

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