The causes of pinkeye include bacteria and viruses, allergies, and irritation due to chemicals and foreign objects, says Mayo Clinic. A blocked tear duct can cause pinkeye among the newborn babies.
Pinkeye that results from bacteria or viruses may attack one or both eyes and is very contagious, according to Mayo Clinic. An individual develops viral or bacterial conjunctivitis through direct or indirect contact with infected eye discharge. Although bacterial and viral conjunctivitis attack both children and adults, the former attacks children more than adults. Additionally, while both bacterial and viral conjunctivitis may result in colds and respiratory infection symptoms, viral conjunctivitis is accompanied with watery eye discharge as opposed to bacterial conjunctivitis, which leads to a yellow-green discharge that is relatively thick.
Pollen is one allergen that may lead to pinkeye, reports Mayo Clinic. Allergic conjunctivitis occurs when the body responds to an allergen by releasing immunoglobulin E antibody, which stimulates the release of inflammatory substances such as histamines from the eye mast cells.
Although pinkeye may not often affect a sufferer's vision, those who are afflicted with pinkeye mostly experience excessive tear production and itchy eyes, explains Mayo Clinic. Eye redness and eye discharge are other common symptoms of pinkeye.