Common Eye Disorders > Conjunctivitis
What causes conjunctivitis?
There are three common causes of conjunctivitis
Bacterial conjunctivitis is an infection caused by bacteria such as staphylococci, streptococci or haemophilus. These organisms may come from the patient’s own skin or upper respiratory tract or they may be caught from another person with conjunctivitis. If your infection is bacterial, your doctor may prescribe antibiotic eye drops as treatment, and the infection should clear within several days. Antibiotic eye ointment is sometimes prescribed in children. An ointment is often easier to administer to an infant or young child than are eye drops, though they may blur vision for up to 20 minutes after application. With either form of medication, you should notice a marked improvement in signs and symptoms within one to two days. Be sure to use the medication for the entire time your doctor prescribes it, to prevent recurrence of the infection.
Viral conjunctivitis is often associated with the common cold. This may be caused by a virus called ‘adenovirus’. This type of conjunctivitis can spread rapidly from one eye to the other and between people, and may cause an epidemic of conjunctivitis. Viral conjunctivitis doesn’t respond to treatment with antibiotic eye drops or ointment. Like with a common cold, you can use an over-the-counter remedy to relieve some symptoms, but the virus just has to run its course. You may notice a worsening of symptoms in the first three to five days. After that, your signs and symptoms should gradually clear on their own. It may take up to two to three weeks from the time you were infected for the virus to go away.
Allergic conjunctivitis is common in people who have other signs of allergic disease such as hay fever, asthma and eczema. The conjunctivitis is often caused by antigens like pollen, dust mites or cosmetics. Your doctor may prescribe one of many different types of eye drops. These may include antihistamines, decongestants, mast cell stabilizers, steroids and anti-inflammatory drops.