Definition of Conjunctivitis
Conjunctivitis is the inflammation of the conjunctiva (the membrane that lines the eyelids and covers the exposed surface of the eyeball). Conjunctivitis can be caused by allergies, bacteria, viruses, chemicals, or underlying health conditions.
The eyes are susceptible to infection because they are not sterile. They rely on lysozyme (an enzyme found in the tears) to destroy bacteria. Bacteria line the surface of the eyelids (all the way down into the shaft of the eyelashes), which makes the conjunctiva predisposed to germs and conjunctivitis
Causes and Risk Factors of Conjunctivitis
Conjunctivitis can be classified as infectious or non-infectious.
Infectious conjunctivitis (pinkeye) accounts for 70 percent of all cases and is caused by either a bacteria (usually staphylococci, pneumococci, streptococci or Chlamydia trachomatis) or a virus.
Bacterial conjunctivitis occurs in 50 percent of all cases, and viral conjunctivitis occurs in 20 percent. Infectious conjunctivitis is very contagious.
Non-infectious conjunctivitis (which accounts for the remaining 30 percent of all cases), can be caused by allergies (such as pollen or grass), chemicals (such as air pollutants, smoke or household cleaners), or underlying diseases (such as rheumatoid arthritis, cytomegalovirus (CMV), lupus, Kawasaki's disease, ulcerative colitis or Crohn's disease.
Additionally, conjunctivitis can be caused by haemorrhaging from trauma or changes in pressure within the head (subconjunctival haemorrhage).
An incompletely opened tear duct or herpetic conditions (such as herpes simplex or herpes zoster) also can cause conjunctivitis.
Symptoms of Conjunctivitis
The symptoms of infectious conjunctivitis caused by a bacteria or viruses include:
- Eye pain
- Swelling of the eyes
- Redness in the eyes
- Yellow, green or watery discharge from the eyes which collects overnight and crusts over the eye
- A gritty feeling in the eye
- Itching of the eye
- An enlarged lymph gland in front of the ear
The symptoms of conjunctivitis caused by allergies include:
- Intense itching of the eye
- Excessive tearing of the eye
- Swelling of the eye
- Redness of the eye
- Runny nose
Symptoms for the other causes of non-infectious conjunctivitis are dependent on the circumstances (i.e., if the conjunctivitis is caused by smog, the person may experience itchy, red eyes; if the conjunctivitis is caused by a chemical in the eye, the person may experience burning, red eyes and blurred vision).
This is not by any means a definitive list of symptoms; it is just a rough guide.
Treatment of Conjunctivitis
Treatment of conjunctivitis varies with the cause. A full optometric examination is imperative in making the correct diagnosis and in determining the exact cause so that treatment is tailored accurately