Eye Infections: Symptoms, Causes and Treatments
Conjunctivitis, styes, keratitis... Mainly caused by viruses or bacteria, eye infections cause unpleasant and painful symptoms. So it's important to seek medical advice as soon as the first signs of eye infection appear. So what is an eye infection? How can you tell if you have an eye infection? And why consult a doctor?
What is an eye infection?
The eyes are made up of a number of structures and tissues, which can be infected by a variety of micro-organisms (bacteria, viruses, fungi or parasites). In particular, these germs can infect part of the eyeball, the cornea (the transparent front surface of the eye) or the conjunctiva (the thin membrane that lines the outer eye and the inside of the eyelids). The term “ocular infectious diseases” is used to describe all these pathologies.
Most often, these harmful germs are carried by the hands: contamination occurs when the person touches or rubs the eyes. Germs can also enter the eye after more or less severe trauma, or after eye surgery. Wearing contact lenses, for example, is one of the minor traumas that can encourage germs to enter the eye. Finally, neurological contamination (with the constant presence of a virus in the body, as in the case of corneal herpes or ophthalmic shingles) is also a possibility.
What are the most common eye infections?
More or less serious, eye infections can affect different parts of the eye and be caused by different infectious agents. Here's a closer look at the main eye infections.
Stye
A stye is an eye infection caused by bacteria (usually staphylococci). It consists of a small swelling on the edge of the eyelid, at the root of an eyelash (pilosebaceous follicle). The edge of the eyelid becomes red and swollen, and a small, painful bump the size of a barley seed appears (hence the term “stye”). The eye becomes sensitive to light and itches. After a few days, the pus pocket opens up and the stye heals.
Very common, this eye infection is frequent in diabetics and immunocompromised people (who are more susceptible to infection). Its appearance is also favored by the wearing of contact lenses or make-up, and in cases of repeated eye rubbing or dry eyes. Styes are not serious and heal quickly with simple local hygiene care.
If it is also a localized blepharitis (inflammation of the eyelid), the stye should not be confused with a chalazion. A painful bump on the eyelid, a chalazion occurs when a Meibomius gland (located in the eyelid, it secretes a fatty substance which, along with tears, lubricates the surface of the eye) becomes engorged. Chalazion is an inflammatory reaction that is not infectious in origin. Although it may resolve spontaneously within a few weeks, it often requires surgical removal.
Infectious conjunctivitis
Conjunctivitis is an inflammation of the conjunctiva, the membrane that covers the white part of the eye and the inside of the eyelids. It can be allergic, irritant, viral or bacterial in origin (the latter being rarer). This common infection causes a number of characteristic symptoms: itching and redness in one or both eyes, swelling of the eyelids, a stinging or gritty sensation in the eyes, a clear or purulent discharge from the eye, eyelids that stick together when you wake up...
Viral conjunctivitis is common and can be caused by a variety of viruses (childhood diseases such as measles or rubella, adenovirus, herpes labialis virus, etc.). It generally affects both eyes, but is not harmful to vision.
More rare, bacterial conjunctivitis is often caused by streptococcus or staphylococcus. It usually affects just one eye (but can later spread to both), and produces thick, yellow, purulent secretions.
While infectious conjunctivitis heals spontaneously within a few days, with local treatment, the infection can spread to the cornea and cause keratitis (a complication that can endanger eyesight). It is therefore important to seek medical advice in the event of conjunctivitis. Infectious conjunctivitis is also contagious. A number of hygiene measures must therefore be adopted during the healing period.
Infectious keratitis
Keratitis is an inflammation of the cornea, the transparent membrane beneath the conjunctiva, in front of the iris and pupil. It can be caused by trauma or allergy, but also by bacterial or viral infection (herpes or shingles). Infectious keratitis causes a number of symptoms: a red, painful eye, reduced vision and intolerance to light (photophobia). Its onset is often encouraged by contact lens wear (due to a lack of hygiene in their care and handling).
If keratitis is caused by a virus, it heals spontaneously within a few weeks (except in the case of shingles or herpes virus infection, in which case the doctor will prescribe treatment). In the case of bacterial infection, antibiotics may be prescribed. The most serious forms may require hospitalization (particularly in the case of abscesses), as they can be vision-threatening.
Other infections
There are other, less frequent eye infections:
- orbital cellulitis: infection of the tissues in the orbit, around or behind the eye. Causing several types of symptoms (pain and swelling, redness of the eyes, fever, blurred vision...), it can spread from the sinuses or originate from an infection of the teeth. Dangerous, it is treated with antibiotics and sometimes requires rapid hospital treatment;
- uveitis: inflammation of any part of the pigmented inner lining of the eye (uvea or uveal tract, which includes the iris). This eye infection causes pain, erythema, the sensation of “flying flies” or floating bodies in the eye, and loss of vision. Treatment is generally based on the administration of corticosteroids (eye drops, orally or injected into or around the eye), with instillation of eye drops to relax the pupil, and immunosuppressive drugs;
- endophthalmitis: the most serious form of eye infection, this is an inflammation of the inside of the eye. It causes severe pain, erythema and loss of vision. Rare, this infection requires hospitalization, with infusions and injections of antibiotics inside the eye (and sometimes surgery).
When should you consult?
It's always advisable to consult your GP or ophthalmologist if you have any symptoms, or if you have any doubts. If left untreated, certain eye infections can lead to serious complications, including permanent loss of vision.
It is therefore important to seek medical advice as soon as the following symptoms appear:
- pain, red eyes, a feeling of sand under the eyelids, itching, swollen eyelids;
- watery or very dry eyes, clear liquid secretions or purulent yellow discharge, eyelids that stick together when you wake up in the morning;
- difficulty tolerating light, reduced vision, blurred vision.
While waiting for the consultation, it is advisable to remove contact lenses (and wear glasses instead). The doctor will carry out a thorough examination (intensity and circumstances of onset of symptoms, contact lens wear, recent trauma, history of infection, etc.). He then performs a complete ophthalmological examination, to confirm his diagnosis and prescribe the appropriate treatment. In the presence of symptoms suggestive of keratitis or uveitis, or when symptoms are severe or do not improve despite treatment, the GP refers the patient to an ophthalmologist.
How is an eye infection treated?
The aim of treating an eye infection is to eliminate the infection, relieve its symptoms, avoid possible complications and reduce the risk of transmission.
Bacterial eye infections are generally treated with prescription eye drops, ointments or antibiotic compresses. Viral infections often disappear on their own (with regular washing with saline solution). The doctor may prescribe antiviral drops for severe infections, or steroid drops to reduce inflammation.
In all cases, it's advisable not to touch the eye while it's healing, and to avoid wearing make-up or contact lenses. Before carrying out any prescribed treatment, be sure to wash your hands thoroughly (with soap and lukewarm water). Eye drops and local antibiotics should never be used without medical advice. In the event of pain, you can take a painkiller (such as paracetamol, if there are no contraindications). To find out more about these medications, ask your doctor or pharmacist.
Finally, there are a number of hygienic measures you can take to prevent the transmission of certain eye infections (notably viral or bacterial conjunctivitis): avoid touching your eyes, wash your hands frequently, discard make-up used prior to infection, and wash towels and sheets frequently.