Medical Definition of Red eye
Red eye: Also called conjunctivitis. Redness or irritation of the conjunctivae, the membranes on the inner part of the eyelids and the membranes covering the whites of the eyes. These membranes react to a wide range of bacteria, viruses, allergy-provoking agents, irritants and toxic agents. Viral and bacterial forms of conjunctivitis are common in childhood.
The leading cause of a red eye is virus infection. Viral pink eye is usually associated with more of a watery discharge, not green or yellow in color, and is frequently associated with viral cold-like symptoms. The eyelids may be swollen. Sometimes looking at bright lights is painful. While viral pink eye, may not require an antibiotic, the doctor should see the child, as occasionally this form of pink eye can be associated with infection of the cornea, (the clear portion of the front of the eyeball). This infection must be correctly detected and treated. Viral pink eye is highly contagious.
The bacteria that most commonly cause pink eye are staphylococcus, pneumococcus, and streptococcus. Symptoms include eye pain, swelling, redness, and a moderate to large amount of discharge, usually yellow or greenish in color. The discharge commonly accumulates after sleep. The eyelids may be stuck together requiring a warm wash cloth applied to the eyes to remove the discharge.
Chlamydia is a form a bacterial that is an uncommon form of pink eye in the U.S., but is very common in Africa and the Middle Eastern countries. It can cause pink eye in adults and neonates. It is a cause of pink eye in adolescents and adults that can be sexually transmitted.
Allergic pink eye is usually accompanied by intense itching, tearing, and swelling of the eye membranes. Frequent causes include seasonal pollens, animal dander, and dust. It is frequently seasonal, and goes along with other typical "allergy" symptoms such as sneezing, itchy nose, or scratchy throat.
Chemical pink eye can result when any irritating substance enters the eyes. Common offending irritants are household cleaners, sprays of any kind, smoke, smog, and industrial pollutants. Prompt, thorough washing of the eyes with very large amounts of water is very important.
Persistent conjunctivitis can be a sign of an uncommon underlying illness in the body. Most often these are rheumatic diseases, such as rheumatoid arthritis and systemic lupus erythematosus. Conjunctivitis is also seen in Kawasaki's disease (a rare disease associated with fever in infants and young children) and certain inflammatory bowel diseases such as ulcerative colitis and Crohn's disease.
Bright redness of the whites of the eyes can also occur when the tiny blood vessels covering the whites of the eyes rupture from trauma or changes in pressure within the head (for example, after forceful laughing or vomiting, when diving under water, or even bending upside down). This condition is called subconjunctival hemorrhage, and, while it can appear impressive, it is generally harmless.
Quick GuideCommon Eye Problems and Infections
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