A corneal infection can damage the clear front of the eye. Pain, redness, light sensitivity or reduced vision need urgent attention.
Seek urgent eye care
A painful red eye, light sensitivity, sudden blurred vision or a white spot on the cornea needs urgent same-day eye assessment, especially if you wear contact lenses. Remove your lenses and do not reinsert them. If urgent eye care is unavailable, attend an emergency department. Sudden loss of vision requires emergency care immediately. Do not wait for a routine appointment or try leftover drops. CDC warning signs | Moorfields urgent advice
What are corneal infection and corneal ulcer?
The cornea is the clear window at the front of the eye. Microbial keratitis means infection of this tissue. A corneal ulcer is a loss of surface tissue that may occur with infection. The terms overlap, but an ulcer does not always have an infectious cause. These conditions can leave scarring and, in severe cases, cause lasting loss of sight. American Academy of Ophthalmology EyeWiki
Symptoms
Symptoms may include increasing pain, redness, watering or discharge, a foreign-body sensation and reduced vision. A white spot may be visible over the coloured part of the eye, but absence of a visible spot does not make symptoms safe to ignore. Contact-lens discomfort that continues after removing the lens also needs attention. Moorfields | CDC
Causes and risk factors
Bacteria, fungi, viruses and parasites can infect the cornea. Contact-lens wear, especially incorrect care or prolonged wear, increases risk. An eye injury or pre-existing surface problem can also contribute. Water exposure while wearing lenses can introduce organisms such as Acanthamoeba. CDC infection information | CDC water guidance
How is it diagnosed?
An eye specialist assesses the cornea and the severity of the problem. A small sample may be taken after numbing drops to identify the organism. Treatment may begin before results return and can change when laboratory findings or follow-up examinations provide more information. Moorfields diagnosis information
General treatment options
Treatment targets the cause. Bacterial infection commonly requires intensive antibiotic drops; fungal, viral or parasitic infections need different medicines. Severe damage may require procedures or surgery. Follow-up checks are important because worsening infection can threaten the cornea even while treatment is being adjusted. AAO EyeWiki
Use medicines exactly as instructed, keep every requested review and seek help if pain, redness or vision worsens. Do not restart lenses until your clinician says it is safe. Moorfields
Preventing another infection
Keep lenses away from tap water; remove them before showering or swimming. Clean and disinfect reusable lenses and cases as directed with appropriate products. Never use water as lens solution. Review your lens routine with your eye-care professional. CDC prevention guidance
Corneal Infection and Ulcer: Urgent Symptoms and Treatment illustrated
Questions for the treating team
- What cause is suspected, and were samples needed?
- What is my exact treatment and follow-up plan?
- Who should I contact immediately if I get worse?
Frequently asked questions
Is this the same as conjunctivitis?
No. Corneal infection affects the clear front window and can be sight-threatening. CDC
Can it leave a scar?
Yes, scarring can occur even with appropriate treatment. Moorfields
Can I put lenses back in when the eye feels better?
Wait for clearance from the treating clinician. CDC
This page is educational. Suspected corneal infection needs examination, not online diagnosis.
Sources and further reading
- Moorfields Eye Hospital: Microbial Keratitis
- CDC: What Causes Contact Lens-related Eye Infections
- American Academy of Ophthalmology EyeWiki: Bacterial Keratitis
- CDC: Keeping Water Away from Contact Lenses
General educational information prepared October 2026. Treatments described are general options; availability and suitability require an individual assessment.
