Conjunctivitis (commonly called "pink eye" or "Madras eye") is an acuteinflammation of the conjunctiva (the outermost layer of the eye and the inner surfaceof the eyelids),most commonly due to an allergic reaction or an infection(usually viral,but sometimes bacterial).While this article relates generally to humans, animals such as canines (dogs) and cattle canexperience this condition
Signs and symptoms
Redness (hyperaemia), irritation (chemosis) andwatering (epiphora) of the eyes are symptoms common to allforms of conjunctivitis.
Allergic conjunctivitis is typically itchy, sometimes distressingly so, andoften involves some eye swelling. Chronic allergy often causes just itching orirritation.
Allergic conjunctivitis shows pale watery swelling or edema of theconjunctiva and sometimes the whole eyelid, often with a ropy, non-purulent mucoid discharge. Thereis variable redness.
Viral conjunctivitis is oftenassociated with an infection of the upper respiratorytract, a common cold, and/or a sore throat.Its symptoms include watery discharge and variable itch. The infection usuallybegins with one eye, but may spread easily to the other.
Viral conjunctivitis, commonly knownas "pink eye", shows a fine diffuse pinkness of the conjunctiva whichis easily mistaken for the ciliary infection or iritis.
Bacterial conjunctivitis due to thecommon pyogenic(pus-producing) bacteria causes marked grittiness or irritation and a stringy,opaque, grey or yellowish mucopurulent discharge (mucus, gowl,goop, gunk, eye crust,or other regional names, officially known as 'gound') that maycause the lids to stick together (matting),especially after sleeping. Another symptom that could be caused by bacterialconjunctivitis is severe crusting of the infected eye and the surrounding skin.However discharge is not essential to the diagnosis, contrary to popularbelief. The more acute pyogenic infections can be painful. Like viralconjunctivitis, it usually affects only one eye but may spread easily to theother eye. However, it is dormant in the eye for three days before the patientshows signs of symptoms.
Irritant or toxic conjunctivitis is irritable or painful when the infectedeye is pointed far down or far up. Discharge and itch are usually absent. Thisis the only group in which severe pain may occur.
Irritant or toxic conjunctivitis show primarily marked redness. If due tosplash injury, it is often present only in the lower conjunctival sac.