Bacterial keratitis
The most common serious corneal infection, and overwhelmingly a contact lens problem: overnight wear, poor hygiene, water exposure and worn lenses give bacteria a way through the surface. It progresses fast, with pain, discharge and a white infiltrate that can become an ulcer within a day. Cultures are taken and fortified antibiotic drops are started immediately, hourly at first. Treated early it usually heals with a small scar; treated late it can threaten the eye.
Herpes simplex keratitis
The herpes simplex virus that causes cold sores can infect the cornea, producing a branching surface ulcer with pain, watering and light sensitivity, and, in recurrent disease, inflammation in the deeper stroma that scars. It is treated with antiviral drops or tablets, and patients with recurrent episodes take a long term suppressive antiviral to protect the cornea. Steroids are used carefully and only for the stromal form, under specialist supervision, because they worsen the surface form.
Herpes zoster ophthalmicus
Shingles affecting the forehead and eye can involve the cornea, causing surface lesions, stromal inflammation and, later, reduced corneal sensation that leads to neurotrophic keratitis. It is treated with oral antivirals started within 72 hours of the rash, and the eye is monitored for months afterward. The shingles vaccine reduces the risk in older adults.
Fungal keratitis
Less common, but serious and slow to respond. It follows injury with plant material, soil or organic matter, and occasionally contact lens wear or steroid use. The infiltrate is often feathery with satellite lesions. Diagnosis needs cultures or special stains, treatment uses antifungal drops for weeks, and deep infections sometimes need surgery. Patients with an eye injury from a branch, thorn or garden debris should mention it specifically.
Acanthamoeba keratitis
A rare infection by an amoeba in tap water, hot tubs and lakes, almost exclusively in contact lens wearers who rinse lenses in water, swim or shower in them. It causes severe pain out of proportion to the signs and is often mistaken for herpes early on. Treatment uses specialized anti-amoebic drops for months. Never rinsing lenses in water and never wearing them in water prevents it.
What to do now
A red, painful, light-sensitive eye, especially in a contact lens wearer, should be examined the same day. Remove the lens, do not put in leftover drops, and call. Bring your lenses, case and solution; they are cultured too.
Is this right for your eyes?
Nothing on this page is a diagnosis. Whether this is what is affecting your vision is decided by a full examination at one of our 4 offices: Pasadena, Huntington Beach, Woodland Hills and Beverly Hills.
About this content: This page was written with the assistance of AI tools and reviewed for medical accuracy by Dr. Bavand Youssefzadeh, DO. It is general information, not medical advice, and does not replace an eye examination. Individual results vary. Read our medical disclaimer.
