Conjunctivitis

Conjunctivitis typically manifests as a combination of inflammatory signs in one or both eyes. Symptoms vary depending on the cause of the inflammation.
The most common signs are:

• red eyes;
• a stinging sensation or feeling of grit in the eyes;
• watery eyes;
• itching;
• sensitivity to light;
• a discharge that is sometimes thick and can stick the eyelids together when you wake up.

These symptoms can affect one or both eyes. They vary depending on the cause. For example, if the cause is viral, the discharge is often clear and runny. On the other hand, if it is a bacterial infection, the secretions are thicker, yellowish or greenish in color, and both eyes can be affected quickly. Allergic conjunctivitis, on the other hand, mainly causes severe itching, often accompanied by swelling of the eyelids. It often occurs in the spring or at certain times of the year, depending on the allergens involved. In some cases of viral conjunctivitis, a small painful lymph node may appear in front of the ear, or a thin film may form inside the eyelid, which a doctor will be able to identify.

Conjunctivitis can have several causes. Here are the main ones:

Infections

These are by far the most common cause. In adults, viruses, particularly adenovirus, are responsible for the majority of cases (up to 90%). These infections are highly contagious and can be transmitted by simple hand contact.
In children, bacteria (such as Streptococcus pneumoniae or Haemophilus influenzae) are more likely to be the cause.

Allergies

Allergic forms result from a reaction triggered by exposure to allergens such as pollen, dust mites, or animal hair. The eyes may react by becoming red, watery, and, above all, very irritated. This type of conjunctivitis affects between 15 and 40% of the population and often recurs at the same time each year.

Irritation

Some forms of conjunctivitis are neither infectious nor allergic. They are caused by an irritant: a chemical, smoke, dust, or even a foreign body (such as an eyelash). These forms are usually temporary and improve as soon as the eye is cleaned or the irritant is removed.

Certain situations or habits increase the risk of developing conjunctivitis. Contact with an infected person is the main source of transmission of viral or bacterial conjunctivitis. This can occur through hands, tissues, or even shared towels.
Seasonal or chronic allergies are also a risk factor. People with respiratory allergies such as hay fever are often affected by allergic conjunctivitis.
Poor hygiene or prolonged wear of contact lenses promotes the development of bacterial infections.
In infants, a tear duct that is still closed at birth can promote spontaneous conjunctivitis.

In most cases, a simple clinical examination allows the doctor to identify conjunctivitis. Observation of the eyes, questioning about symptoms, and the patient's history are sufficient to make the diagnosis.

In case of doubt, particularly if the eye is very painful, highly sensitive to light, or vision is impaired, the doctor may seek a specialist opinion. This allows other more serious conditions such as keratitis (inflammation of the cornea) or uveitis to be ruled out.

For certain forms, a sample of the eye discharge may be taken to identify the causative organism, particularly if the infection does not improve with first-line treatment.

The choice of treatment depends on the cause of the conjunctivitis.
If it is viral:
There is no specific treatment. In most cases, symptoms disappear within one to two weeks. Comfort measures may be recommended: eye washing with saline solution, cold compresses, and visual rest.

If it is bacterial:
The doctor may prescribe antibiotic eye drops or ointment, especially if the symptoms are severe or have lasted for several days. This treatment shortens the duration of the infection and limits its transmission.

If it is allergic:
Antihistamine or anti-inflammatory eye drops are often effective. It is also recommended to avoid exposure to identified allergens. In cases of persistent allergy, long-term treatment or desensitization may be considered.

Finally, for all forms of conjunctivitis, it is advisable to:

• Wash your hands regularly.
• Avoid touching or rubbing your eyes.
• Do not share towels or makeup products.

In most cases, conjunctivitis clears up on its own within a few days to two weeks, depending on its cause. Viral forms take the longest to disappear, but they usually resolve without specific treatment. Bacterial infections respond well to antibiotics. If left untreated, some bacterial infections can worsen, especially in frail or immunocompromised individuals. A rarer but serious complication is keratitis, an inflammation of the cornea. It can occur following viral conjunctivitis (especially adenovirus) or in people who wear contact lenses during an infection. Keratitis can cause intense pain, severe photophobia, and decreased vision. It requires prompt medical evaluation.
Conjunctivitis that does not improve, causes significant discomfort, or is accompanied by decreased vision should therefore always be taken seriously.Une conjonctivite qui évolue mal, provoque une gêne importante ou s’accompagne d’une baisse de vision doit donc toujours être prise au sérieux.

Several simple measures can help limit the risk of contracting or transmitting conjunctivitis. Washing your hands frequently, not touching your eyes, and avoiding sharing toiletries can help reduce the risk of infection. Wearing contact lenses requires strict hygiene rules. In the case of allergies, avoiding known allergens remains the best preventive strategy.

Most cases of conjunctivitis heal on their own or with local treatment. However, certain signs should raise alarm and warrant a prompt consultation:

• if vision is blurred or diminished;
• if significant pain is felt in the eye;
• if photophobia (sensitivity to light) is pronounced;
• if the eye becomes difficult to open due to pain;
• or if symptoms worsen despite several days of treatment.

For contact lens wearers, redness accompanied by discharge should always be taken seriously. This could indicate a potentially serious corneal infection.
In infants, persistent conjunctivitis or conjunctivitis accompanied by fever also requires medical attention.

Is conjunctivitis contagious?
Yes, viral and bacterial conjunctivitis are contagious. They are easily transmitted through direct contact or via shared objects such as towels.

Can conjunctivitis cause vision loss?
In the vast majority of cases, no. Conjunctivitis is a benign condition. However, some severe forms, particularly those caused by allergies that are not properly treated or linked to infections such as herpes or gonorrhea, can damage the cornea.

How long does conjunctivitis usually last?
It depends on the cause. Viral conjunctivitis lasts an average of 7 to 14 days. Bacterial forms often heal more quickly with treatment. Allergic conjunctivitis can recur seasonally or chronically.

Can I go to work or school with conjunctivitis?
As long as symptoms are present (red, watery, or runny eyes), it is best to stay home to avoid infecting others, especially in cases of viral conjunctivitis.

Is allergic conjunctivitis contagious?
No. It is not caused by a microbe but by an immune system reaction to an allergen such as pollen or dust mites.

Should I always see a doctor if I have conjunctivitis?
Not necessarily. If the symptoms are mild and improve within a few days, a consultation is not necessary. However, if you experience pain, decreased vision, or no improvement after a few days, medical advice is recommended.

Can conjunctivitis come back?
Yes. Viral conjunctivitis can sometimes recur if the immune system has not yet completely eliminated the virus. Allergic conjunctivitis can reappear whenever the person is exposed to the allergen responsible.