Keratitis: Symptoms, Causes & Treatment Guide
Updated: 2 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: September 2026
Source currency note: This article reflects clinical guidance last published July 02, 2024.
TL;DR
Keratitis is inflammation of the cornea — the clear, dome-shaped tissue at the front of the eye that covers the pupil and iris. It may or may not involve an infection: minor injuries such as overwearing contact lenses cause noninfectious keratitis, while bacteria, viruses, fungi and parasites cause infectious keratitis. Contact lens habits — especially sleeping in lenses — are the single biggest risk factor. Treatment is matched to the cause: artificial tears for mild scratches, antibiotic, antifungal, antiviral or antiparasitic drops for infections, and a cornea transplant in severe cases. With prompt attention, most mild to moderate cases heal without vision loss — but delays can lead to serious complications, including blindness.
Quick Answer
What is keratitis? Inflammation of the cornea, the clear dome-shaped tissue covering the pupil and iris at the front of the eye.
What does it feel like? Eye redness, pain, excess tears or discharge, blurred or decreased vision, light sensitivity (photophobia), and a feeling that something is in the eye.
What causes it? Injury (like a scratch or foreign body), or infection by bacteria, viruses, fungi or parasites — often tied to contact lens habits or contaminated water.
Who is at risk? Contact lens wearers (especially those who sleep in lenses), people with weakened immunity, corticosteroid eye drop users, and those with past eye injuries.
How is it diagnosed? An eye exam with a penlight (sometimes with a dye stain), a slit-lamp exam, and occasionally lab analysis of tears or cornea cells.
Is it treatable? Yes — most mild to moderate cases respond well to treatment without vision loss if addressed promptly.
When should I see a doctor? Immediately, if you have eye redness or other symptoms — delays can lead to complications including blindness.
What Is Keratitis?
Keratitis is an inflammation of the cornea — the clear, dome-shaped tissue on the front of your eye that covers the pupil and iris.
Importantly, keratitis may or may not be associated with an infection.
Noninfectious keratitis can be caused by a relatively minor injury, such as wearing your contact lenses too long or getting a foreign body in the eye. Infectious keratitis can be caused by bacteria, viruses, fungi and parasites.
The good news is encouraging: with prompt attention, mild to moderate cases of keratitis can usually be effectively treated without loss of vision. The sobering counterpoint is equally clear: if left untreated, or if an infection is severe, keratitis can lead to serious complications that may permanently damage your vision.
Two Forms: Infectious vs. Noninfectious
Before looking at symptoms, it helps to understand the two forms — because the form determines the treatment.
Form | Typical Trigger | Examples |
Noninfectious | A relatively minor injury to the cornea | Wearing contact lenses too long; a foreign body in the eye |
Infectious | Bacteria, viruses, fungi or parasites | Bacterial, viral (herpes), fungal, or acanthamoeba keratitis |
A single injury can actually lead to both: a scratch can cause noninfectious keratitis directly, and the same injury can allow microorganisms to gain access to the damaged cornea, causing infectious keratitis.
What Are the Symptoms of Keratitis?
Symptoms of keratitis include the following.
Symptom | What It Feels Like |
Eye redness | The white of the eye looks red or bloodshot |
Eye pain | Ranging from irritation to significant discomfort |
Excess tears or other discharge | Watery eyes or drainage from the affected eye |
Difficulty opening your eyelid | Because of pain or irritation |
Blurred vision | Vision that comes and goes out of focus |
Decreased vision | Vision that is noticeably reduced |
Sensitivity to light (photophobia) | Normal light feels uncomfortable or harsh |
A feeling that something is in your eye | Like grit or an eyelash is stuck — even when nothing is there |
If you've worn contact lenses recently and feel like something is stuck in your eye, resist the urge to keep rubbing or to power through it. That sensation is one of keratitis's hallmark signals — and it is one worth acting on quickly.
When to see a doctor
If you notice any of the symptoms of keratitis, make an appointment to see an eye specialist right away.
Delays in diagnosis and treatment of keratitis can lead to serious complications, including blindness.
What Causes Keratitis?
Five mechanisms appear in the source material, and together they explain nearly every case.
Injury. If any object scratches or injures the surface of your cornea, noninfectious keratitis may result. In addition, an injury may allow microorganisms to gain access to the damaged cornea, causing infectious keratitis.
Bacteria, fungi or parasites. These organisms may live on the surface of a contact lens or contact lens carrying case. The cornea may become contaminated when the lens is in your eye, resulting in infectious keratitis. Poor contact lens hygiene or contact lens overwear can cause both noninfectious and infectious keratitis.
Viruses. The herpes viruses — herpes simplex and herpes zoster — may cause keratitis.
Bacteria. Staphylococcus, streptococcus and pseudomonas are common bacteria involved in keratitis.
Contaminated water. Bacteria, fungi and parasites in water — particularly in oceans, rivers, lakes and hot tubs — can enter your eyes when you're swimming and result in keratitis. However, even if you're exposed to these organisms, a healthy cornea is unlikely to become infected unless there has been some previous breakdown of the corneal surface — for example, from wearing a contact lens too long.
Risk Factors for Keratitis
Factors that may increase your risk of keratitis include the following four.
Risk Factor | What the Evidence Shows |
Contact lenses | Wearing contacts — especially sleeping in them — increases risk of both infectious and noninfectious keratitis; risk stems from wearing them longer than recommended, improper disinfection, or wearing them while swimming |
Reduced immunity | A weakened immune system due to disease or medications raises risk |
Corticosteroids | Corticosteroid eye drops used to treat an eye disorder can increase the risk of infectious keratitis or make existing keratitis worse |
Eye injury | A cornea damaged from a past injury is more vulnerable to developing keratitis |
The contact lens finding deserves emphasis. Keratitis is more common in people who use extended-wear contacts, or wear contacts continuously, than in those who use daily wear contacts and take them out at night. That single habit comparison tells you where most of your prevention power lives.
Complications of Untreated Keratitis
Understanding the stakes makes the urgency concrete. Potential complications of keratitis include:
Complication | What It Means |
Chronic corneal inflammation and scarring | Long-term inflammation that leaves permanent marks on the cornea |
Chronic or recurrent viral infections of the cornea | Viral keratitis that returns repeatedly |
Corneal ulcers | Open sores on your cornea |
Reduced vision | Temporary or permanent reduction in your vision |
Blindness | In the most severe, untreated cases |
How Is Keratitis Diagnosed?
Diagnosing keratitis typically involves the following four steps.
Test | What Happens | What It Reveals |
Eye exam | Your eye care provider examines your eyes — important even if opening your eyes is uncomfortable | Overall assessment |
Penlight exam | A penlight checks your pupil's reaction, size and other factors; a stain may be applied to the surface of your eye | Used with the light, the stain makes damage to the cornea surface easier to see |
Slit-lamp exam | A special instrument called a slit lamp provides bright light and magnification | The character and extent of keratitis, and its effect on other structures of the eye |
Laboratory analysis | A sample of tears or cells from your cornea is taken for lab analysis | The cause of keratitis, which helps develop your treatment plan |
The pattern is logical: look first, illuminate the damage, measure its extent, then identify the exact cause — because the cause decides the treatment.
How Is Keratitis Treated?
Noninfectious keratitis
Treatment of noninfectious keratitis varies depending on the severity. For example, with mild discomfort from a corneal scratch, artificial tear drops may be the only treatment. However, if keratitis is causing significant tearing and pain, topical eye medications may be necessary.
Infectious keratitis
Treatment of infectious keratitis varies, depending on the cause of the infection.
Cause | Primary Treatment | Details |
Bacterial | Antibiotic eye drops | Drop frequency ranges from about four times a day to every 30 minutes, even during the night, depending on severity; oral antibiotics sometimes supplement |
Fungal | Antifungal eye drops + oral antifungal medication | Typically both topical and oral treatment are required |
Viral | Antiviral eye drops + oral antiviral medications | Some other viruses need only supportive care such as artificial tear drops |
Acanthamoeba (parasite) | Antiparasitic eye drops | Can be difficult to treat; some infections resist medication and require months of treatment; severe cases may require a cornea transplant |
The range of treatment intensity is striking — from drops every 30 minutes through the night for severe bacterial cases, to months-long therapy for resistant parasitic infections.
Cornea transplant
If keratitis doesn't respond to medication, or if it causes permanent damage to the cornea that significantly impairs your vision, your eye care provider may recommend a cornea transplant.
How Can Keratitis Be Prevented?
Caring for your contact lenses
If you wear contact lenses, proper use, cleaning and disinfecting can help prevent keratitis. Follow these tips:
Prevention Step | The Rule |
Lens type | Choose daily wear contacts and take them out before going to sleep |
Hand hygiene | Wash, rinse and dry your hands thoroughly before handling your contacts |
Professional guidance | Follow your eye care provider's recommendations for taking care of your lenses |
Cleaning products | Use only sterile products made specifically for contact lens care, made for the type of lenses you wear |
Lens replacement | Replace your contact lenses as recommended |
Case replacement | Replace your contact lens case every 3 to 6 months |
Solution hygiene | Discard the solution in the case each time you disinfect; don't "top off" old solution |
Swimming | Don't wear contact lenses when you go swimming |
The "topping off" habit deserves special mention because it is so common: reusing old solution in the case dilutes its disinfecting power and can harbor the very organisms that cause keratitis.
Preventing viral outbreaks
Some forms of viral keratitis can't be completely eliminated. But the following steps may control viral keratitis occurrences:
Prevention Step | The Rule |
Cold sores and blisters | If you have a cold sore or a herpes blister, avoid touching your eyes, eyelids and the skin around your eyes unless you've thoroughly washed your hands |
Eye drops | Only use eye drops that have been prescribed by an eye doctor |
Hand washing | Washing your hands frequently can reduce viral outbreaks |
Preparing for Your Appointment
You may start by seeing or calling your health care provider if you have eye-related symptoms that worry you. Depending on the type and severity of your symptoms, your provider may refer you to an eye specialist, called an ophthalmologist.
What you can do
Be aware of any pre-appointment restrictions when you make the appointment — ask if there's anything you need to do in advance, such as stop wearing contact lenses or stop using eye drops. Write down any symptoms you're experiencing, including any that may seem unrelated to the reason for which you scheduled the appointment. Make a list of all medications, including vitamins and supplements that you're taking. And write down questions to ask.
Questions to ask
Your time is limited, so preparing a list of questions can help you make the most of your appointment. Some basic questions to ask include: What is likely causing my symptoms? What are other possible causes for my symptoms? What kinds of tests do I need? What is the best course of action? What are the alternatives to the approach you're suggesting? I have other health conditions — how can I best manage them together? Are there any restrictions that I need to follow? Should I see a specialist? Is there a generic alternative to the medicine you're prescribing? Are there any brochures or other printed material I can take with me? What websites do you recommend? What will determine whether I need to be seen for a follow-up visit?
In addition to the questions you've prepared, don't hesitate to ask other questions anytime you don't understand something.
What to expect from your doctor
Doctor's Question | Why It Matters |
When did symptoms begin? Are they continuous or occasional? | Establishes the timeline |
How severe are your symptoms? What improves or worsens them? | Gauges urgency |
Has your eye been injured recently? | Screens for noninfectious triggers |
Have you been swimming or in a hot tub recently? | Screens for contaminated-water exposure |
Do you use contact lenses? Do you sleep in them? How do you clean them? | The single most informative cluster of questions |
How often do you replace your contact lens storage case? | Checks lens hygiene habits |
Have you had a similar problem in the past? | Suggests recurrent or viral patterns |
Are you using eye drops now or have you used any recently? | Screens for corticosteroid exposure |
How is your general health? Ever had a sexually transmitted infection? | Screens for immune factors |
Have you recently changed the type of cosmetics you are using? | Screens for product-related triggers |
Conclusion
Keratitis is a condition where the stakes are entirely tied to timing. The cornea — the eye's clear protective dome — inflames for reasons ranging from a harmless-feeling scratch to a sleeping-in-your-lenses habit, to contaminated lake water, to a herpes virus reactivation. The symptoms are recognizable — redness, pain, discharge, light sensitivity, and that persistent "something in my eye" feeling.
And the treatment picture is genuinely encouraging: most mild to moderate cases heal without vision loss when treated promptly. Even the treatment menu is logical — drops matched to the cause, oral medicines when needed, and surgery only in the cases that resist everything else.
The prevention half is even more empowering, because the dominant risk factor — contact lens habits — is almost entirely within your control.
If you have eye redness, pain, or vision changes — especially if you wear contact lenses — see an eye specialist right away. Early treatment is the difference between a quick recovery and permanent vision damage.
Frequently Asked Questions
What is keratitis?
Keratitis is an inflammation of the cornea — the clear, dome-shaped tissue on the front of your eye that covers the pupil and iris. It may or may not be associated with an infection.
What are the symptoms of keratitis?
Symptoms include eye redness, eye pain, excess tears or discharge, difficulty opening your eyelid because of pain, blurred or decreased vision, light sensitivity (photophobia), and a feeling that something is in your eye.
Can contact lenses cause keratitis?
Yes — wearing contact lenses, especially sleeping in them, increases your risk of both infectious and noninfectious keratitis. The risk typically stems from wearing them longer than recommended, improper disinfection, or wearing them while swimming. Extended-wear and continuous-wear contacts carry higher risk than daily-wear lenses removed at night.
Is keratitis contagious?
The infectious forms are caused by bacteria, viruses, fungi or parasites — some of which, like the herpes viruses, can pass between people. But the condition itself typically requires a vulnerable cornea, such as one damaged by a scratch or by overwearing contact lenses.
How is keratitis diagnosed?
An eye exam, a penlight exam (sometimes with a dye stain applied to the eye surface), a slit-lamp exam using a special magnifying light instrument, and sometimes laboratory analysis of tears or cornea cells to determine the exact cause.
How is keratitis treated?
It depends on the cause. Noninfectious keratitis may need only artificial tear drops or topical eye medications. Bacterial keratitis is treated with antibiotic eye drops. Fungal keratitis typically needs antifungal drops plus oral antifungal medication. Viral keratitis may use antiviral drops and oral antivirals. Acanthamoeba keratitis, caused by a parasite, can require months of antiparasitic treatment.
Is there a cure for keratitis?
Most mild to moderate cases can be effectively treated without loss of vision when addressed promptly. If keratitis doesn't respond to medication or causes permanent corneal damage that significantly impairs vision, a cornea transplant may be recommended.
What happens if keratitis is left untreated?
Delays in diagnosis and treatment can lead to serious complications — chronic inflammation and scarring, corneal ulcers, temporary or permanent vision reduction, and in severe cases, blindness.
References
Keratitis — Symptoms and causes (Mayo Clinic, published July 02, 2024)
Keratitis — Diagnosis and treatment (Mayo Clinic, published July 02, 2024)
Rinnit.com provides general health information for educational purposes. This content does not replace professional medical advice — always consult a qualified healthcare provider for diagnosis and treatment.
Health information, not medical advice. This article is for general education and is not a substitute for professional diagnosis or treatment. Always consult a qualified healthcare provider about your own health, and seek emergency care for urgent symptoms.
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