Conjunctivitis The term conjunctivitis refers to any inflammatory condition of the membrane that lines the eyelids and covers the exposed surface of the sclera, and is the most common cause of "red eye" or "pink eye" (Abbott pp). Most often the etiology can be determined by a careful history and an ocular examination, however, culture is sometimes necessary to establish the diagnosis or to guide therapy (Abbott pp). The most common causes of conjunctivitis are bacteria and viruses (Abbott pp). When severe, bilateral, purulent conjunctivitis is present in a sexually active adult or in a neonate three to five days postpartum, then Neisseria infection should be suspected (Abbott pp). Conjunctivitis that is caused by Chlamydia trachomatis or Neisseria gonorrhoeae requires aggressive antibiotic therapy, however, conjunctivitis due to other bacteria is usually self-limited (Abbott pp). Chronic conjunctivitis is most often associated with blepharitis, recurrent styes or meibomianitis, and treatment requires good eyelid hygiene and the application of topical antibiotics as determined by culture (Abbott pp). The discomfort with viral or bacterial conjunctivitis can be soothed by applying warm compresses using a clean cloth soaked in warm water to closed eyes (Conjunctivitis pp). Allergic conjunctivitis is characterized by severe itching and allergen exposure and is generally treated with topical antihistamines, mast-cell stabilizers or anti-inflammatory agents (Abbott pp).

Cellular infiltration and exudation characterize conjunctivitis on a cellular level. Classification usually is based on cause, including viral, bacterial, fungal, parasitic, toxic, chlamydial, chemical, and allergic agents. It also can be based on age of occurrence or course of disease. Etiology often can be distinguished on clinical grounds. In keratoconjunctivitis,

an associated corneal involvement is present

(Silverman pp).

The conjunctiva is a thin, translucent, relatively elastic tissue layer with both bulbar and palpebral portions, the bulbar portion fines the outer aspect...

The conjunctiva firmly adheres to the sclera at the limbus, where it meets the cornea, and the accessory lacrimal glands, along with goblet cells, are contained within the conjunctiva and are responsible for keeping the eye lubricated (Silverman pp). "As with any mucous membrane, infectious agents may adhere to the conjunctiva, thus overwhelming normal defense mechanisms and producing clinical symptoms of redness, discharge, irritation, and possibly photophobia" (Silverman pp).
The hallmark of allergic conjunctivitis is itching, which may be mild to sever, and usually a red eye in the absence of itching is not caused by ocular allergy (Abbott pp). "A history of recurrent itching or a personal or family history of hay fever, allergic rhinitis, asthma or atopic dermatitis is also suggestive of ocular allergy" (Abbott pp). Mild itching can also be a feature of blepharitis, dry eyes and, occasionally, bacterial or viral conjunctivitis (Abbott pp). The type of discharge, such as serous, mucoid, mucopurulent or grossly purulent, can be helpful in determining the underlying cause of conjunctival inflammation (Abbott pp). A mucoid, or stringy discharge is characteristic of allergy or dry eyes, while a mucopurulent or purulent discharge, usually associated with morning crusting and difficulty opening the eyelids, suggests a bacterial infection (Abbott pp).

Allergic conjunctivitis is almost always secondary to environmental allergens, and so usually present with bilateral symptoms (Abbott pp). Infections caused by viruses and bacteria are transmissible by eye-hand contact, with infections initially present in one eye, followed by infection of the second eye a few days later (Abbott pp).

Chronic unilateral conjunctivitis can have a number of causes and is difficult to diagnose, therefore, patients with this condition should be referred for full ophthalmic assessment to rule our less common…