Eye Infections: Bacterial, Fungal and Viral
Eye infections occur when harmful microorganisms — bacteria, fungi and viruses — invade any part of the eyeball or surrounding tissues, including the clear front surface of the eye (cornea) and the thin membrane lining the outer eye and inner eyelids (conjunctiva).
Eye infection symptoms
Common symptoms of eye infections include:
Swelling around the eyes
Anytime you suspect an eye infection, you should always visit your eye doctor for an eye exam. Trying to self-diagnose your condition can delay effective treatment and potentially cause permanent vision loss.
There are many different types of eye infections, and your eye doctor needs to determine the particular type of eye infection you have in order to prescribe the proper treatment.
Your doctor may take a sample from the affected area of your eye for a culture to assess the exact type of infection you have, if any. This may help determine the most effective treatment, such as an antibiotic that selectively targets the type of bacteria causing the infection.
Causes and types of eye infections
Examples of viral, fungal and bacterial eye infections include:
Pink eye, or conjunctivitis. Conjunctivitis, also called "pink eye," is a common, highly contagious eye infection that often is spread among children in day care centers, classrooms and similar environments. Teachers and day care workers also are at increased risk of pink eye when they work in close quarters with young children. Common infectious conjunctivitis types often have viral or bacterial origins. Infants also can acquire conjunctival eye infections (gonococcal and chlamydial conjunctivitis) during birth when a mother has a sexually transmitted disease.
Fungal keratitis. This type of eye infection made worldwide news in 2006 when a contact lens solution now withdrawn from the market was linked to an outbreak among contact lens wearers. The fungal eye infection was associated with Fusarium fungi, commonly found in organic matter. This and other fungi can invade the eye in other ways, such as through a penetrating injury caused by a tree branch.
Acanthamoeba keratitis. Contact lens wearers are at increased risk of encountering parasites that can invade the eye and cause a serious sight-threatening infection called Acanthamoeba keratitis. This is why contact lens wearers should observe certain safety tips, such as avoiding swimming while wearing contacts. If you do wear contact lenses when swimming or relaxing in a hot tub, make sure you remove and disinfect your lenses immediately afterward. Indeed, there is an increased risk of fungal and bacterial eye infections among contact lens wearers in general, and proper contact lens care must be followed. FDA guidelines recommend that manufacturers include a discard date (not just a date of expiration) on contact lens cleaning and disinfecting products to help minimize the risk of eye infection.
Trachoma. A serious eye infection known as trachoma, related to Chlamydia trachomatis, is a leading cause of blindness in certain parts of the world. The infection us spread by flies in unsanitary environments and reinfection is a common problem. Trachoma typically infects the inner eyelid, which begins to scar. Scarring then causes an "in-turning" of the eyelid, and eyelashes begin to brush against and destroy tissue on the cornea, with resulting permanent blindness. Good hygiene and availability of treatments such as oral antibiotics are essential to controlling trachoma.
Endophthalmitis. Usually caused by bacteria, endophthalmitis is a serious infection of the interior of the eye. The most common cause of endophthalmitis is a penetrating eye injury. It also can occur as a rare complication of eye surgery such as cataract surgery.
Prompt medical treatment with potent antibiotics is required to prevent serious vision loss or even blindness from endophthalmitis.
Eye Infection Complications
An infection also can affect interior portions of the upper and lower eyelids to create a stye or chalazion. Rubbing or “popping” a stye should be avoided, as this can cause a deeper, more serious infection called orbital cellulitis. Orbital cellulitis is an infection of the tissues around the eyeball. It is a medical emergency because, if not promptly treated, in can cause blindness, meningitis and even death.
Infection also can lead to inflammation and blockage of the eye's tear drainage system and cause dacryocystitis.
Eye infection treatments
Fortunately, most common bacterial eye infections can be effectively treated with prescription antibiotic eye drops or ointments and compresses.
Many common viral eye infections resolve on their own. In cases of severe viral eye infections, an antiviral eye drop may be prescribed. Some viral eye infections require careful administration of steroid eye drops to reduce related inflammation.
Depending on the underlying cause of your eye infection, your doctor may prescribe antibiotics or antiviral medications that are taken orally. If your symptoms worsen or change, contact your eye doctor immediately.
How to prevent eye infections
If you are near a person with a red eye, do not touch your own eyes until you wash your hands first. You also can minimize the likelihood of catching common bacterial or viral eye infections by avoiding rubbing your eyes, washing your hands frequently throughout the day (especially before applying and removing contact lenses), cleaning towels and bed linens often, and using anti-bacterial cleaning products on countertops and other common areas.
Page published in December 2019
Page updated in January 2022