What is keratitis?
Keratitis is infection or inflammation of the cornea. Microbial keratitis — caused by bacteria, viruses, fungi or parasites — can destroy corneal tissue quickly. A scar in the line of sight can permanently blur vision; severe infection can perforate the eye. This is why red flags are taken seriously and treated urgently.
Causes and risk factors
The most important modern risk factor is contact-lens wear — especially overnight wear, poor lens hygiene, or swimming/showering in lenses. Other risks include corneal injury by vegetative matter (plant material, soil — raising fungal risk), previous corneal disease or surgery, weakened immunity (including diabetes), and steroid eye-drop use without supervision. Viral keratitis, commonly from herpes simplex, can recur and needs antiviral therapy.
Warning signs that need same-day care
Eye pain that is more than mild, a red eye, reduced or blurred vision, discharge, light sensitivity, a white or grey spot on the clear cornea, or any of these in a contact-lens wearer — seek assessment the same day. Rinse chemical splashes for 15–20 minutes with clean water first, then seek care immediately.
How infection is diagnosed
The slit-lamp examination maps the ulcer’s size, depth and location. Where the organism is not obvious, a corneal scraping may be taken — a brief procedure — and sent for smear and culture to identify bacteria or fungus and guide precise therapy. Viral keratitis is usually recognised by its characteristic pattern. Early treatment is often started on clinical suspicion even before lab results return.
Treatment approach
Treatment is targeted and intensive: frequent antimicrobial drops (sometimes fortified, made for the specific organism), oral antivirals for herpetic disease, and cycloplegic drops for comfort. Steroids are used cautiously and only when appropriate, as they can worsen infection. Review frequency is high at first — every day or two in active ulcers — because response guides whether therapy is escalated. Healed infections may leave scars needing later optical rehabilitation; severe cases may eventually need corneal transplantation once the infection has resolved.
Prevention
Most contact-lens-related keratitis is preventable: never sleep in lenses unless specifically prescribed, wash and dry hands before handling, use fresh solution daily, replace cases regularly, keep lenses away from water, and stop wear immediately if the eye becomes red or uncomfortable. Treat ocular allergies to reduce rubbing, and never use leftover or someone else’s eye drops.