Conjunctivitis is a term that literally means “inflammation of the conjunctiva”, also commonly known as “red eye” or “pink eye”. The conjunctiva is the thin, transparent membrane that covers the white part of the eye (the sclera) as well as the underside of the upper and lower eyelids. In addition to being a protective tissue, the conjunctiva produces mucous to lubricate the surface of the eye. Fine blood vessels normally traverse within the conjunctiva. When the conjunctiva becomes irritated or inflamed, these blood vessels become engorged and more prominent. The appearance of the eye then becomes red. There are multiple causes of conjunctivitis. These include infectious, allergic, dry eye syndrome, exposure to an irritant or part of a systemic disorder. The conjunctiva responds to all these stimuli the same way, by turning red.
Infectious conjunctivitis may be caused either by a bacteria or a virus. Bacterial infections, such as those caused by staphylococcus or streptococcus, cause an acutely inflamed, red eye associated with pus. Other types of bacterial infections may be without a significant discharge and more chronic in nature. Viral infections typically present as red eyes with a watery discharge. These are commonly associated with swollen glands, a sore throat or a runny nose. Infectious conjunctivitis, whether bacterial or viral, can be quite contagious via an infected person’s tears. Separate towels and pillow cases are recommended as well as avoiding contact with commonly handled objects such as telephones or keyboards. Handwashing is essential in helping prevent the spread of infection.
Allergic conjunctivitis consists of various forms such as hayfever, vernal and atopic. Hayfever conjunctivitis is characterized by rapid onset when exposed to an allergen (i.e. grass). With prompt treatment, hayfever is usually short-lived. Vernal conjunctivitis occurs seasonally (spring and fall) upon exposure to various pollens. This condition lasts weeks and treatment should be initiated early in its course. Atopic conjunctivitis is a chronic allergic condition. It usually affects the patient throughout their life and is associated with asthma and eczema. Symptoms common to all forms of allergic conjunctivitis are redness, swelling, tearing and itching.
Dry eye syndrome is an extremely common cause of conjunctivitis and persistent red eyes. Dry eye syndrome is caused by decreased tearing as well as exposure to dry, hot air. This condition occurs in many people including (but not limited to) contact lens wearers, women going through menopause, people who have arthritis and those taking anti-histamines or anti-depressants.
Exposure to chemicals, vapor or smoke can induce conjunctivitis. It is important to wear safety glasses whenever handling potentially dangerous products. Lastly, conjunctivitis can be associated with systemic conditions such as various forms of arthritis, inflammatory bowel disease, various systemic viral infections (i.e. chicken pox), auto-immune diseases (i.e. lupus) and from trauma.
It is important to realize that a red eye may be something different than a case of simple conjunctivitis. A red eye may be part of a more serious problem such as iritis (inflammation of the front chamber of the eye), keratitis (an infection of the cornea) or episcleritis/scleritis (inflammation of the tissue underneath the conjunctiva). Symptoms such as pain, light sensitivity and/or blurred vision usually indicate a more serious condition. Thus whenever a red eye presents, a thorough evaluation by a qualified eye doctor is thus recommended in order to determine its cause. Once the underlying cause is determined, specific treatment will be initiated.