Conjunctivitis

Conjunctivitis is an inflammation or infection of the conjunctiva which can be caused by bacteria, viruses, chemical aggressions or drug reactions.

The conjunctiva is a thin, transparent membrane that lines the inner surface of the eyelids (palpebral conjunctiva) and the anterior scleral surface, i.e. the white part of the eyeball (bulbar conjunctiva). Its function is to protect our eyes from external agents and to lubricate the surface of the eye.

Types of Conjunctivitis

Conjunctivitis can be allergic, bacterial, viral, or fungal, according to the causative microbial agent.

Viral or bacterial conjunctivitis is the result of an infection and is therefore very contagious.

Generally, viral conjunctivitis is caused by adenovirus and can, in some situations, be associated with a clinical picture with the presence of fever, sore throat and discomfort. The secretion produced in the eyes is whitish and has a small quantity. In bacterial conjunctivitis, on the other hand, caused by numerous bacteria such as Staphylococcus aureus, the secretion produced is yellowish, purulent and in larger quantities.

Allergic conjunctivitis is caused by contact with allergenic agents, such as pollen, animal hair, cleaning products, among others. Allergic conjunctivitis is not contagious and the secretion produced has a watery consistency.

The classification may still vary according to the criteria used:

• Acute, subacute and chronic, according to the way they start and develop over time;
• Serous, mucous, purulent and psedomembranous, according to the type of secretion produced;
• Follicular, papillary, flictenular or giant papillary, according to the structural alterations of the mucosa or the tissue reaction produced;

The signs and symptoms of conjunctivitis vary from person to person according to the severity, the pathogenicity of the infectious agent as well as the immune system and tolerance capacity of each patient.

The most common symptoms are:

• Foreign body sensation;
• Hyperaemia (red eye);
• Pruritus (itching);
• Tearing;
• Eyelid oedema (swelling);
• Secretion production (which usually forms a kind of crust during the night, causing the patient to wake up with gluey and sticky eyes)
• Pain;
• Decreased visual acuity may occur (due to accumulation of conjunctival secretions) but is less common.
• Photophobia (sensitivity to light);

The inflammatory process of this pathology causes vasodilatation of the blood vessels of the conjunctiva (causing the typical red eye) and an increase in vascular permeability with consequent oedema and production of secretions. In addition, irritation causes the conjunctival glands to increase their activity, leading to a greater aqueous (tear), serous (exudation), mucous (mucin), mucopurulent or purulent secretion, depending on the microbial agent.

In some cases, the prolonged evolution of inflammation can lead to more specific morphological alterations.

Anyone can get conjunctivitis. However, people with allergies and prolonged contact lens wearers can be considered risk factors. Clinical conditions include blepharitisectropion, entropion and dacryocystitis may favour the development of inflammation.

Diagnosis is made by medical observation. In this type of situation a slit lamp biomicroscopy is usually used. The ophthalmologist may use a coloured eye drops (fluorescein) to check for corneal lesions.

The treatment of conjunctivitis should be appropriate according to the causative agent. In most cases, the conjunctiva treatment is topical, through the application of drops and/or ointments. Under no circumstances should self-medication be used to solve conjunctivitis. Always consult your ophthalmologist so that he/she can indicate the best treatment.

There are some behaviours you should observe so as not to aggravate the infection, such as:

• Wash your hands frequently;
• Do not wear contact lenses;
• Wash your eyelids regularly so that no secretions accumulate;
• Avoid rubbing or scratching your eyes;