Eye Infection: The Complete Guide to Symptoms, Causes, Diagnosis and Treatment
Updated: 3 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: November 2026
Quick Answer
An eye infection is a disease of the eye caused by a microorganism such as a bacterium, virus or fungus. The most common is pink eye (conjunctivitis), usually caused by viruses, and antibiotics only work on bacterial infections. Sleeping in contact lenses is a common cause. Infections involving the cornea or an eye injury can be emergencies that threaten vision.
What the research says
Overnight wear raises infection risk even with daily disposable lenses. In a multisite case-control study of 67 cases of microbial keratitis and 374 controls, all daily disposable contact lens wearers, independent risk factors included any overnight wear (odds ratio 1.8), less frequent hand washing (odds ratio 1.8), and smoking (odds ratio 1.3) (PubMed: Stapleton et al., PLoS One, 2017 [1]).
Everyday lens habits matter for the most serious infection, too. In a case-control study of Acanthamoeba keratitis (83 cases and 122 controls), the odds were higher for daily-wear reusable soft lenses (odds ratio 3.84) than for daily disposable lenses, and among daily disposable users, risk factors included lens reuse (odds ratio 5.41), overnight wear (odds ratio 3.93), and showering in lenses (odds ratio 3.29) (PubMed: Carnt et al., Ophthalmology, 2023 [2]).
New lens technology has not lowered the infection rate. A 2019 American Academy of Optometry think tank concluded that the absolute rate of contact lens-associated microbial keratitis has stayed very consistent for three decades, that extended wear significantly increases the risk, and that compliance with lens care remains a significant risk factor (PubMed: Szczotka-Flynn et al., Optom Vis Sci, 2021 [3]).
What Is an Eye Infection? An Overview
An eye infection is a disease of the eye that you get because of a microorganism like a bacterium, a virus or a fungus. The most common eye infection is pink eye (conjunctivitis) [4].
Viruses cause most cases of pink eye, but bacteria can cause pink eye, too. An important practical note: you can't treat viral infections with antibiotics. Antibiotics only work on bacterial infections [4].
Eye infections can happen in one eye or both eyes. Some infections aren't serious. Others are medical emergencies that can cause vision loss. Eye infections can affect nearly any part of your eye, including your eyelid, your conjunctiva or cornea, or the external parts of your eye [4].
Key Point | What It Means |
Definition | A disease of the eye caused by a microorganism — bacterium, virus or fungus |
Most common type | Pink eye (conjunctivitis), usually viral |
Antibiotics | Only work on bacterial infections — not viral ones |
One eye or both | Either is possible |
Severity | Some aren't serious; others are medical emergencies that can cause vision loss |
Where it happens | Nearly any part of the eye — eyelid, conjunctiva, cornea or external parts |
How common | Common — about 1 million people in the U.S. get care for eye infections each year, and many involve contact lens wearers |
How common are eye infections?
Eye infections are common. About 1 million people in the U.S. go to their healthcare providers or to hospitals with eye infections each year. Many of these infections happen to people who wear contact lenses [4].
What are some common eye infections?
The most common eye infections include [4]:
Eye Infection | What It Is |
Blepharitis | Inflammation of the eyelid margins |
Cellulitis | Infection of the skin and tissue around the eye |
Dacryocystitis | An infection of your tear sac that can happen when your tear ducts become blocked and can't drain properly |
Pink eye (conjunctivitis) | The most common eye infection; usually viral |
Endophthalmitis | A serious infection inside the eye |
Stye | A painful bump on the eyelid caused by infection |
Uveitis | Inflammation of the eye's middle layer |
Symptoms of Eye Infections
An infected eye may look or feel different than usual. The signs progress from early irritation to more serious symptoms as the infection develops.
Stage | Sign or Symptom | What It Looks Like |
Early | Red eyes | The white of the eye turns red or pink |
Early | Itching or irritation | A scratchy, uncomfortable feeling in or around the eye |
Early | Eye pain | Aching or soreness in the eye |
Early | Watery eyes | Excess tearing |
Early | Swelling | Puffiness around the eye or eyelids |
Later | Discharge | Yellow, sticky pus from your eyes |
Later | Eyelashes sticking together | Eyelashes clumped together because of discharge |
Later | Light sensitivity (photophobia) | Bright light becomes painful |
Later | Blurred vision | Your vision becomes unclear |
Later | Fever | An elevated body temperature |
Early eye infection symptoms include red eyes, itching or irritation, eye pain, watery eyes and swelling. Later symptoms include yellow sticky pus discharge, eyelashes sticking together, light sensitivity (photophobia), blurred vision and fever [4]. Seek care if symptoms progress beyond the early stage.
What Causes Eye Infections?
You can get eye infections from bacteria, fungi (plural of fungus), parasites and viruses. These small organisms can enter your eyes in many different ways, including eye injuries [4].
One of the most common ways to get an eye infection is to sleep in your contact lenses. It's also common to get an eye infection if you don't properly clean your lenses [4].
Cause Category | Key Organisms | Notes |
Bacteria | Bacillus, Enterobacteriaceae, Haemophilus influenzae, Moraxella spp., Neisseria gonorrhoeae, Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus pneumoniae | Both gram-negative and gram-positive bacteria cause eye infections |
Viruses | Herpes simplex type 1, Varicella zoster virus, Adenovirus | Viruses cause most cases of pink eye |
Fungi | Candida species, Fusarium | Candida causes about 66% of endophthalmitis cases after corneal transplant surgery; you might also get a fungal infection after cataract surgery |
Parasites | Various parasites | Less common but possible |
What bacteria commonly cause eye infections?
Both gram-negative and gram-positive bacteria can cause eye infections [4]. Gram-negative and gram-positive bacteria are told apart by how they stain in a Gram stain test, and both can be detected in a bacterial culture test.
Some of the more common bacterial causes of infections in your eyes include Bacillus, Enterobacteriaceae, Haemophilus influenzae, Moraxella spp., Neisseria gonorrhoeae, Pseudomonas aeruginosa (P. aeruginosa), Staphylococcus aureus (S. aureus) and Streptococcus pneumoniae (S. pneumoniae) [4].
What viruses commonly cause eye infections?
The common viral causes are herpes simplex type 1, varicella zoster virus and adenovirus [4].
What types of fungi cause eye infections?
Fungi belonging to the Candida species cause about 66% of endophthalmitis cases that happen after corneal transplant surgery [4]. You might also get a fungal infection after cataract surgery [4].
You can get an eye infection if you have an eye injury because of an item from the outdoors, such as a stick or a plant, contaminated with Fusarium. You can also get an eye infection that happens because of a fungal bloodstream infection [4].
How Are Eye Infections Diagnosed?
You might be able to tell if you have an eye infection, but it's best to consult a healthcare provider. Your provider will take your medical history, ask you questions about your symptoms and do a thorough eye exam. They may also take a swab of any discharge from your eye to send to a lab for testing [4].
Diagnostic Step | What Happens |
Medical history | Your provider reviews your health background, including contact lens use |
Symptom questions | Questions about redness, discharge, pain, vision changes and how long symptoms have lasted |
Eye exam | A thorough exam of the eye's structures |
Discharge swab (when needed) | A swab of discharge from your eye sent to a lab for testing |
How Are Eye Infections Treated?
Treatment for eye infections depends on what's causing your eye infection. It might include anti-infective medication in various forms, such as eye drops, ointments or tablets. It usually takes 24 to 48 hours for antibacterial medications to work [4].
You may have to let viral or allergic infections clear on their own, but you may be able to make yourself more comfortable with the following home remedies [4]:
Home Remedy | How It Helps |
Damp, warm or cool compresses | Makes your eyes feel better |
Lubricating eye drops (artificial tears) | Relieves dryness and irritation |
Over-the-counter (OTC) pain relievers | Eases eye pain and fever |
Avoiding allergens | Removes the trigger that caused the allergic reaction in the first place |
Outlook and Prognosis
What to expect depends heavily on the type of infection.
Infection Type | Contagious? | Risk to Sight | What To Do |
Allergy-related | Not contagious; not dangerous to your sight; no need to avoid other people | Low | Comfort care, allergy medicine |
Viral, bacterial or fungal | Can spread to other people; avoid being around others until you treat your condition | Varies | Anti-infective treatment, hygiene measures |
Corneal infections and infections from eye injuries | Varies | Dangerous to your vision | Contact an eye care specialist promptly — these need expert evaluation |
Can Eye Infections Be Prevented?
You may not be able to prevent every eye infection, but you can take steps to reduce your risk.
Prevention Step | Why It Matters |
Follow contact lens directions | Use, cleaning and wear-time rules prevent most lens-related infections; never sleep in your lenses |
Wear protective eye gear | Protects your eyes when you work or participate in sports |
Avoid allergens and take allergy medicine | Prevents allergic irritation that mimics infection |
Avoid people who may be ill | Reduces exposure to contagious eye infections |
Practice good hand hygiene | Stops germs from reaching your eyes |
Don't share towels or eye makeup | Prevents transferring organisms between people |
Throw out cosmetics after an infection | Avoids getting re-infected |
Living With Eye Infections
If you have allergies, you might be familiar with eye irritation. But it's a good idea to see your healthcare provider about any eye condition that's causing discomfort, pain, discharge or problems with your vision [4].
You'll need immediate medical help for eye injuries. In some instances, you'll need treatment to prevent certain eye infections causing vision loss. Oftentimes, eye doctors are available "on call" after hours or on weekends to address these types of vision-threatening infections [4].
Important: Even though you may be familiar with symptoms of redness or irritation in your eye, it's important to have a healthcare provider examine you and diagnose what's causing the problem. Some eye infections can cause serious problems without proper treatment. People who wear contact lenses should be especially careful.
Take the Next Step
Find an eye care specialist today if you're experiencing eye discomfort, pain or discharge. An eye care specialist can determine the exact cause and find the correct treatment before a routine infection becomes a vision-threatening emergency.
Conclusion: Don't Guess — Get It Checked
Eye infections are common — about 1 million people in the U.S. seek care for them every year, and many involve contact lens wearers. They're caused by bacteria, viruses or fungi, and the most common is pink eye, which is usually viral and won't respond to antibiotics. Most infections clear within 24 to 48 hours of antibacterial treatment or resolve on their own with comfort care, and you can reduce your risk through contact lens hygiene, hand washing and not sharing eye products. But because some eye infections — especially those involving the cornea or an eye injury — are medical emergencies that can cause vision loss, the safest step is always to have a healthcare provider examine and diagnose the problem.
Related on Rinnit: Eye Diseases: The Complete Guide · Pink eye · Cellulitis · Dacryocystitis · Stye · Uveitis · Watery eyes (epiphora) · Adenovirus
Further reading: Cleveland Clinic — Eye Infection
Frequently Asked Questions
1. What is an eye infection?
An eye infection is a disease of the eye caused by a microorganism like a bacterium, a virus or a fungus. The most common eye infection is pink eye (conjunctivitis). Viruses cause most cases of pink eye, but bacteria can cause it too — and antibiotics only work on bacterial infections, not viral ones.
2. How common are eye infections?
Eye infections are common. About 1 million people in the U.S. go to their healthcare providers or hospitals with eye infections each year. Many of these infections happen to people who wear contact lenses.
3. What are the symptoms of an eye infection?
Early symptoms include red eyes, itching or irritation, eye pain, watery eyes and swelling. Later symptoms include yellow sticky pus discharge, eyelashes sticking together, light sensitivity (photophobia), blurred vision and fever.
4. What causes eye infections?
Bacteria, fungi, parasites and viruses cause eye infections, and these organisms can enter your eyes in many ways, including eye injuries. One of the most common ways to get an eye infection is sleeping in your contact lenses; improper lens cleaning is also common.
5. Can I treat a viral eye infection with antibiotics?
No. You can't treat viral infections with antibiotics — antibiotics only work on bacterial infections. Viral and allergic infections must clear on their own, though compresses, artificial tears and OTC pain relievers can make you more comfortable.
6. How are eye infections treated?
Treatment depends on the cause and may include anti-infective medication in forms such as eye drops, ointments or tablets. Antibacterial medications usually take 24 to 48 hours to work. Viral or allergic infections clear on their own with comfort measures like compresses and artificial tears.
7. How long does an eye infection last?
With antibacterial treatment, eye infections usually start improving within 24 to 48 hours. Viral and allergic infections clear on their own over days to weeks. Contact your provider if symptoms persist or worsen.
8. Are eye infections contagious?
Eye infections due to viruses, bacteria or fungi can spread to other people, so you should avoid being around others until you treat your condition. Eye infections due to allergies are not contagious and are not dangerous to your sight.
9. What are the most dangerous eye infections?
Eye infections involving the cornea and infections from eye injuries are dangerous to your vision and require prompt evaluation by an eye care specialist. Eye injuries need immediate medical help, and eye doctors are often available on call after hours for vision-threatening infections.
10. What types of fungi cause eye infections?
Fungi in the Candida species cause about 66% of endophthalmitis cases after corneal transplant surgery, and you might also get a fungal infection after cataract surgery. You can also get an infection from an outdoor item like a stick or plant contaminated with Fusarium, or from a fungal bloodstream infection.
11. How can I prevent eye infections?
Follow contact lens directions for use, cleaning and wear time; wear protective eye gear at work and sports; avoid allergens; avoid people who may be ill; practice good hand hygiene; don't share towels or eye makeup; and throw out cosmetics if you develop an infection to avoid re-infection.
References
Stapleton F, Naduvilath T, Keay L, et al. Risk factors and causative organisms in microbial keratitis in daily disposable contact lens wear. PLoS One. 2017;12(8):e0181343. doi:10.1371/journal.pone.0181343. PMID: 28813424.
Carnt N, Minassian DC, Dart JKG. Acanthamoeba keratitis risk factors for daily wear contact lens users: a case-control study. Ophthalmology. 2023;130(1):48-55. doi:10.1016/j.ophtha.2022.08.002. PMID: 35952937.
Szczotka-Flynn LB, Shovlin JP, Schnider CM, et al. American Academy of Optometry Microbial Keratitis Think Tank. Optom Vis Sci. 2021;98(3):182-198. doi:10.1097/OPX.0000000000001664. PMID: 33771951.
Cleveland Clinic. Eye infection. Cleveland Clinic Health Library. Medically reviewed; last updated May 11, 2023. https://my.clevelandclinic.org/health/diseases/25000-eye-infection
Medical Disclaimer
This article is for informational purposes only and does not constitute medical advice. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read here.
Comments