Conjunctivitis: All You Need to Know

Conjunctivitis is a condition that affects a structure of the eye known as the conjunctiva. It can be caused by different factors, such as viruses or bacteria, among others.
Conjunctivitis: All You Need to Know

Written by Equipo Editorial

Last update: 07 August, 2021

Conjunctivitis is an eye condition that can sound alarming. However, this common eye problem is generally easy to treat. Also, with a series of easy preventive measures, in most cases, it can be prevented.

Anyone can get conjunctivitis. However, young children, college students, teaching staff, and daycare workers are more likely to be infected due to closeness and contact between people.

In a simplified way, it’s the inflammation of the transparent thin covering of the white part of the eye and the inside of the eyelids. This covering is known as the conjunctiva.

The structure of the eye

The human eye is a very complex organ that receives information in the form of light. To better understand conjunctivitis, it’s important to get a bit more familiar with the part of the eye that’s affected by this inflammation.

The conjunctiva is a transparent mucous membrane that covers the white part of the eye or the sclera, which is the ocular structure that constitutes the outermost layer of the eye. Its function is to shape and protect the eye from external agents. The conjunctiva also lines the inside of the eyelids.

The conjunctiva aims to protect the eyeball from external agents, although it also intervenes in the formation of tear components and in the immune defense of the eye.

structure of the eye


As we’ve seen, conjunctivitis is an inflammation of the conjunctiva. However, this inflammation can be due to different causes.

In this sense, we can distinguish 4 types of conjunctivitis:

  • Allergic
  • Bacterial
  • Viral
  • Irritating, or toxic

Despite having different origins, they have common characteristics, such as having red-eye and increased secretions, although these will be different depending on the type of conjunctivitis.

Allergic conjunctivitis

This type of conjunctivitis is caused by eye irritants, such as pollen, dust or animal dander, in susceptible individuals. This type of pathology can be seasonal or outbreaks can appear throughout the year. Allergens cause an inflammation of the blood vessels of the conjunctiva.

In addition to the irritating agents mentioned, soft contact lenses can also cause this type of inflammation. This conjunctivitis isn’t contagious.

Its onset is usually abrupt and bilateral, with the main symptom being intense itching, especially at the inner end, that is, the part of the eye closest to the nose. This itchiness is increased by scratching. Other symptoms are:

  • Crying eyes
  • Temporary blurred vision
  • Swelling of the eyelids, especially in the morning

The characteristic discharge of this type of conjunctivitis is watery or mucous, depending on the intensity.

The diagnosis of this type of conjunctivitis is clinical, but, in the cases that require it, several tests and examinations can be carried out, including:

  • Eosinophil tests, which are a type of white blood cell
  • Detection of small bumps on the conjunctiva when reversing the eyelid
  • Skin reaction tests that test positive for a certain allergen

The treatment will depend on how advanced the conjunctivitis is. The best thing against allergic conjunctivitis is prevention. To do this, it’s essential to know what allergen is causing it, and try to avoid it.

In short, to alleviate the symptoms you can resort to:

  • Using lubricating drops or artificial tears
  • Applying cold compresses to the eyes
  • Not using chamomile infusions as a natural remedy, as they may contain allergic components.
  • Avoiding tobacco smoke.
  • If the doctor deems it necessary, antihistamine and/or corticosteroid eye drops can be administered.

Bacterial conjunctivitis

As the name suggests, this is caused by bacteria. It’s an infection that can cause serious damage if not treated properly. The bacteria involved can be staphylococci, streptococci, or haemophilus.

These microorganisms can come from the patient’s own skin, from their upper airways, or be transmitted by another person who has conjunctivitis. Some rare germs can be very serious like Pseudomonas aeruginosa in contact lens wearers. Diphtheria bacillus in children 1 to 4 years old is also serious.

The discharge is mucopurulent and the onset somewhat more insidious. It’s usually yellowish or yellowish-green and sticky in the same corner as allergic conjunctivitis. In some cases, this discharge can be so abundant that it causes the eyelids to stick together when you wake up.

One or both eyes may be affected. You have to be careful because this conjunctivitis is contagious. Other symptoms are:

The ophthalmologist usually prescribes antibiotic drops or creams for treatment. In difficult-to-resolve or recurrent conjunctivitis, consider a tear duct disorder or infectious eyelid pathology such as blepharoconjunctivitis.

eye drops conjunctivitis

Viral conjunctivitis

This is the most common type of conjunctivitis. It’s very variable, but is usually very florid, with unilateral onset, frequently becoming bilateral after 3 to 7 days. It’s caused by an infection by viruses, which can be different.

It usually starts in one eye and can pass to the other in the following days because it’s highly contagious; it can be spread by coughing or sneezing.

Patients with viral conjunctivitis often have burning and stinging discomfort, profuse tearing, and sensitivity to light. Sometimes it’s accompanied by significant edema of the eyelid. The discharge, in this case, is watery but later it can become somewhat thicker.

In general, the diagnosis is clinical, by identifying the signs and symptoms in the consultation. In addition, there’s a rapid diagnostic test to identify adenovirus on the ocular surface, as it’s the main agent responsible for viral conjunctivitis.

However, the use of this test isn’t very widespread in routine clinical practice. If it’s suspected that it’s bacterial form, then samples of the secretions are usually taken. Doctors will perform a culture that will allow them to know the agent that causes the disease and help them choose an appropriate antibiotic treatment.

In most cases, viral conjunctivitis will continue to run its course over a period of a few days without the need for medical treatment. As a home remedy, cool wet cloths can be applied to the eyes several times a day to relieve symptoms. Be careful not to share the cloths with other people, as it’s highly contagious.

Therefore, the treatment of viral conjunctivitis is symptomatic, focused on improving the quality of life of the patient and preventing complications and infections. In this sense, it’s important to wash the inside of the eye 4-5 times a day with small disposable containers of physiological saline.

Washing must be energetic to flush out all the secretions. The use of artificial tears is also useful to reduce the stinging and discomfort derived from conjunctivitis.

Irritant/toxic conjunctivitis

It’s produced by an inflammation of the eyelid margin or blepharitis, usually caused by the use of cosmetics or by contact with irritants present in the environment, such as solvents, paint, or chlorine, for example.

Treatment, in these cases, consists of avoiding toxic agents associated with the administration of lubricating eye drops such as artificial tears.

  • Toribio, E. (2001). Conjuntivitis alérgica. @BULLET Enero-Febrero @BULLET Enero-Febrero @BULLET Enero-Febrero.
  • Martín Bun, M., Carreño Freire, P., & Saniger Herrera, J. M. (2009). Conjuntivitis. FMC Formacion Medica Continuada En Atencion Primaria.
  • Orden Martínez, B., Martínez Ruiz, R., & Millán Pérez, R. (2004). Conjuntivitis bacteriana: Patógenos más prevalentes y sensibilidad antibiótica. Anales de Pediatria.
  • Epling, J. (2012). Bacterial Conjuntivitis. BMJ.

Este texto se ofrece únicamente con propósitos informativos y no reemplaza la consulta con un profesional. Ante dudas, consulta a tu especialista.