What is conjunctivitis?

Conjunctivitis is an inflammation of the conjunctiva, a transparent membrane covering part of the eyeball and the inner part of the eyelids.

The conjunctiva contains small blood vessels that look like thin red lines on the sclera (the white of the eye) and, when inflamed, give the eye a reddish appearance.

Conjunctivitis is a benign disorder that does not affect vision, but can cause complications if not treated properly.

What causes it?

There are as many types of conjunctivitis as there are factors that cause it:

  • Infectious conjunctivitis represents approximately one-third of all conjunctivitis cases and can be caused by bacteria or viruses
  • Allergic conjunctivitis occurs when the eyes are exposed to a substance to which the patient is allergic (an allergen), causing an inflammation of the blood vessels in the conjunctiva. The most common causes are dust mites, pollen and other substances from trees, flowers and plants, as well as fungi and epithelial tissue from animals (shedding). Other causes include dry climates or the use of soft contact lenses
  • Irritant conjunctivitis is caused by an inflammation of the eyelid (blepharitis), usually resulting from the use of cosmetic products or contact with irritants in the environment (solvents, paints, swimming pool chlorine, etc.)

How can it be prevented?

The best preventative measure is to avoid exposure to allergens. When this is not possible, or appropriate measures have not been taken, and any of the described symptoms appear, the patient should consult an ophthalmologist. In the case of infectious conjunctivitis, other measures should also be taken to prevent infection:

  • Not sharing anything that has been in contact with an infected eye (pillowcases, sheets, towels, eye liners, etc.)
  • Washing hands immediately if they have been in contact with someone with conjunctivitis
  • Not allowing children with the infection to go to school
  • Cleaning eye discharges twice a day
  • Not wearing contact lenses or makeup


The most common symptoms of conjunctivitis include redness, itching, the sensation of a foreign body or grit, eyelid swelling, watery eyes and discharges.

Complication symptoms can include external pain when opening and closing the eyelids, photophobia, significant swelling of the eyelids or the sensation of a foreign body.

People affected by bacterial conjunctivitis often suffer from a profuse and thick yellow or greenish discharge, and usually wake up with their eyelids stuck together.

Allergic conjunctivitis causes itching and other nasal allergy symptoms (sneezing, obstruction and watery discharge), as well as bronchial (asthma) or skin (dermatitis) complaints.


Conjunctivitis treatment varies significantly depending on its cause:

Viral conjunctivitis, as with a cold, has no specific treatment, although special care is recommended by the ophthalmologist, who can help control symptoms and prevent complications

Bacterial conjunctivitis, by contrast, is treated with antibiotic eye drops and usually subsides within a week

Allergic conjunctivitis usually responds well to treatment with antihistamines or can disappear by itself if the causative allergen is removed. Symptoms can be alleviated with cold compresses and, in some cases, topical corticosteroids can be prescribed to reduce inflammation

Irritant conjunctivitis can be minimised by eliminating the cause and administering anti-inflammatory treatment until the eye is back to normal


IMO Institute of Ocular Microsurgery

Josep María Lladó, 3
08035 Barcelona
Phone: (+34) 934 000 700
E-mail: international@imo.es
See map on Google Maps

By car

GPS navigator coordinates:
41º 24’ 38” N – 02º 07’ 29” E

Exit 7 of the Ronda de Dalt (mountain side). The clinic has a car park with more than 200 parking spaces.

By bus

Autobus H2: Rotonda de Bellesguard, parada 1540

Autobus 196: Josep Maria Lladó-Bellesguard, parada 3191

Autobuses H2, 123, 196: Ronda de Dalt – Bellesguard, parada 0071

IMO Madrid

C/ Valle de Pinares Llanos, 3
28035 Madrid
Phone: (+34) 910 783 783
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Public transport

Metro Lacoma (líne 7)

  • Lines 49 & 64, stop “Senda del Infante”
  • Line N21, stop “Metro Lacoma”


Patient care:
Monday to Friday, 8 a.m. to 8 p.m.

IMO Andorra

Av. de les Nacions Unides, 17
AD700 Escaldes-Engordany, Andorra
Phone: (+376) 688 55 44
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IMO Manresa

C/ Carrasco i Formiguera, 33 (Baixos)
08242 – Manresa
Tel: (+34) 938 749 160
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Public transport

FGC. Line R5 & R50 direction Manresa. Station/Stop: Baixador de Manresa


Monday to Friday, 08:30 A.M – 13:30 PM / 15:00 PM – 20:00 PM

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