In addition to the cornea and eyelids, the conjunctiva the mucous membrane of the eye also plays a role in moisturizing the ocular surface, forming the tear film, and protecting against irritants and microorganisms. It is a thin, transparent membrane rich in blood vessels. It lines the inner surface of the eyelids and covers the front surface of the eyeball up to the cornea. The conjunctiva does not cover the cornea itself. The space between the eyelids and the eyeball, where tear fluid is constantly present, is called the conjunctival sac.
The conjunctiva is conventionally divided into three regions:
Together, they form the conjunctival sac, which constantly contains tear fluid.
The conjunctiva consists of epithelium, a connective tissue layer, blood vessels, nerve endings, immune system cells, and goblet cells that produce mucins.
What functions does the conjunctiva perform?
Maintenance of the tear film.
Mucins produced by goblet cells help the aqueous component of tears spread evenly and remain on the surface of the eye.
Protection.
The conjunctiva acts as a physical barrier between the ocular surface and the environment, while its immune cells respond to potential threats. Blinking, together with the tear film, helps remove small particles.
Eye mobility.
The folds of the fornices allow the eyeball to move freely and the eyelids to glide smoothly over its surface.
What diseases affect the conjunctiva?
Among the most common are:
Conjunctivitis is inflammation of the conjunctiva. Depending on the cause, the following forms are distinguished:
- Viral. It is most commonly caused by adenoviruses and often accompanies a cold. Typical signs include redness, watery discharge, and a feeling of irritation. The condition may begin in one eye and later spread to the other. It is highly contagious. Treatment is mainly symptomatic (artificial tears, cool compresses). Antiviral eye drops are prescribed only when indicated, for example, in cases of herpetic infection.
- Bacterial. The causative agents include staphylococci, streptococci, and Haemophilus influenzae. Purulent discharge and eyelids sticking together, especially in the morning, are characteristic. It is also contagious through contact with an infected person. It is treated with antibacterial eye drops or ointments as prescribed by a doctor.
- Allergic. It occurs in response to plant pollen, household dust, and other allergens. The main signs are itching, swelling, and tearing. Both eyes are usually affected, sometimes together with allergic rhinitis, and symptoms are often seasonal. It is not contagious. Treatment includes avoiding contact with the allergen, antihistamine eye drops, and mast cell stabilizing eye drops.
- Toxic (irritant). It occurs after contact with chemicals, smoke, certain cosmetic ingredients, or medications. It is not contagious. If a chemical substance gets into the eye, it should be rinsed immediately with clean water and medical attention should be sought.
Dry eye syndrome (keratoconjunctivitis sicca)
This is a disease of the entire ocular surface, involving both the conjunctiva and the cornea. If too few tears are produced, they evaporate too quickly, or their composition changes, symptoms such as burning, dryness, a gritty sensation, fluctuating vision, and photophobia may occur. Sometimes increased tearing is also observed this is how the eye responds to irritation.
Symptoms can be aggravated by prolonged screen use, reduced blinking, dry or air-conditioned environments, contact lenses, certain medical conditions, and medications.
Treatment depends on the cause. It usually includes lubricating eye drops and gels, adjustments to visual workload, and treatment of associated conditions. If the dryness is related to meibomian gland dysfunction, IPL therapy may also be used when indicated.
Pinguecula and pterygium
Prolonged ultraviolet exposure, wind, and chronic irritation of the ocular surface may contribute to the development of both conditions.
Subconjunctival hemorrhage
A bright red spot on the white part of the eye (the sclera) may look alarming, but it usually does not threaten vision and resolves on its own within 1–2 weeks. A hemorrhage may sometimes occur after coughing, sneezing, straining, or rubbing the eyes because the conjunctival blood vessels are thin and fragile. If hemorrhages recur, it is worth checking your blood pressure and consulting a doctor. You should also seek medical attention if the hemorrhage appears after an injury or is accompanied by pain or decreased vision.
Can conjunctivitis be treated at home?
Self-treatment is not recommended. The same symptom, such as redness, can have different causes, including corneal diseases, so it is important to first establish the correct diagnosis. To do this, the doctor examines the ocular surface using a slit lamp and, if necessary, orders additional tests.
Antibiotics do not work against viruses, and corticosteroid eye drops used without a doctor’s prescription can worsen viral eye infections (including herpetic infections), increase intraocular pressure, and damage the cornea.
How can you prevent the spread of infection?
Viral and bacterial conjunctivitis are contagious. To protect yourself and those around you, wash your hands frequently, avoid touching or rubbing your eyes, and use separate towels and cosmetics. Do not wear contact lenses during treatment until your doctor says it is safe to do so.
When should you see a doctor immediately?
A red eye is not always conjunctivitis. If you experience severe eye pain, photophobia, decreased vision, a foreign body sensation, have had an eye injury, or a chemical substance has entered the eye, see an ophthalmologist immediately. You should also not delay a visit if the symptoms do not resolve within a few days or occur in someone who wears contact lenses.
Kushnir Nataliya
Ophthalmologist, Candidate of Medical Sciences