Cambridge Encyclopedia :: Cambridge Encyclopedia Vol. 17
 

conjunctivitis - Epidemiology, Diagnosis, Treatment and management

Inflammation of the membrane covering the inner surface of the eyelids and the front surface of the eye (the conjunctiva). It may be caused by infections, foreign bodies, or chemicals. It results in a feeling of grittiness in the eyes, and is associated with stickiness of the eyelids and a discharge. The whites of the eyes are red and bloodshot.
Portions of the summary below have been contributed by Wikipedia.
Conjunctivitis
Classifications and external resources
An eye with viral conjunctivitis
ICD-10 H10.
ICD-9 372.0-372.3
DiseasesDB 3067
MedlinePlus 001010
eMedicine emerg/110 

Conjunctivitis (commonly called "pinkeye" in the USA and "Madras Eye" in India) is an inflammation of the conjunctiva (the outermost layer of the eye and the inner surface of the eyelids), often due to infection.

Blepharoconjunctivitis is the combination of conjunctivitis with blepharitis.
Keratoconjunctivitis is the combination of conjunctivitis and keratitis.

Epidemiology

There are three common varieties of conjunctivitis, viral, allergic, and bacterial. Other causes of conjunctivitis include thermal and ultraviolet burns, chemicals, toxins, overuse of contact lenses, foreign bodies, vitamin deficiency, dry eye, dryness due to inadequate lid closure, exposure to chickens infected with Newcastle disease, epithelial dysplasia (pre-cancerous changes), and some conditions of unknown cause such as sarcoidosis.

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Viral conjunctivitis is spread by aerosol or contact of a variety of contagious viruses, including many that cause the common cold, so that it is often associated with upper respiratory tract symptoms.

Allergic conjunctivitis occurs more frequently among those with allergic conditions, with the symptoms having a seasonal correlation.

Bacterial conjunctivitis is most often caused by pyogenic bacteria such as Staphylococcus or Streptococcus from the patient's own skin or respiratory flora.

Irritant, toxic, thermal and chemical conjunctivitis are associated with exposure to the specific agents, such as flame burns, irritant plant saps, irritant gases (e.g., chlorine or hydrochloric acid ('pool acid') fumes), natural toxins (e.g., ricin picked up by handling castor oil bean necklaces), or splash injury from an enormous variety of industrial chemicals, the most dangerous being strongly alkaline materials.

Xerophthalmia is a term that usually implies a destructive dryness of the conjunctival epithelium due to dietary vitamin A deficiency—a condition virtually forgotten in developed countries, but still causing much damage in developing countries.

Diagnosis

Symptoms

Redness, irritation and watering of the eyes are symptoms common to all forms of conjunctivitis.

Acute allergic conjunctivitis is typically itchy, sometimes distressingly so, and the patient often complains of some lid swelling.

Viral conjunctivitis is often associated with an infection of the upper respiratory tract, a common cold, or a sore throat.

Bacterial conjunctivitis due to the common pyogenic (pus-producing) bacteria causes marked grittiness/irritation and a stringy, opaque, grey or yellowish mucopurulent discharge (gowl, goop, sleep, or other regional names) that may cause the lids to stick together (matting), especially after sleeping. Like viral conjunctivitis, it usually affects only one eye but may spread easily to the other eye.

Irritant or toxic conjunctivitis is irritable or painful.

Signs

Infection (redness) of the conjunctiva on one or both eyes should be apparent, but may be quite mild.

Allergic conjunctivitis shows pale watery swelling or edema of the conjunctiva and sometimes the whole eyelid, often with a ropy, non-purulent mucoid discharge.

Viral conjunctivitis, commonly known as "pink eye", shows a fine diffuse pinkness of the conjunctiva which is easily mistaken for the 'ciliary injection' of iritis, but there are usually corroborative signs on biomicroscopy, particularly numerous lymphoid follicles on the tarsal conjunctiva, and sometimes a punctate keratitis.

Pyogenic bacterial conjunctivitis shows an opaque purulent discharge, a very red eye, and on biomicroscopy there are numerous white cells and desquamated epithelial cells seen in the 'tear gutter' along the lid margin.

Irritant or toxic conjunctivitis show primarily marked redness.

Differential diagnosis

Conjunctivitis symptoms and signs are relatively non-specific.

Prominent itch and pale watery swelling (edema) of the conjunctiva or eyelids suggests allergy.

A purulent discharge strongly suggests bacterial cause, unless there is known exposure to toxins.

A diffuse, less 'injected' conjunctivitis (looking pink rather than red) suggests a viral cause, especially if numerous follicles are present on the lower tarsal conjunctiva on biomicroscopy.

Scarring of the tarsal conjunctiva suggests trachoma, especially if seen in endemic areas, if the scarring is linear (von Arlt's line), or if there is also corneal vascularisation.

Clinical tests for lagophthalmos, dry eye (Schirmer test) and unstable tear film may help distinguish the various types of dry eye.

Other symptoms including pain, blurring of vision and photophobia should not be prominent in conjunctivitis.

Investigations

These are done infrequently because most cases of conjunctivitis are treated empirically and (eventually) successfully, but often only after running the gamut of the common possibilities.

Swabs for bacterial culture are necessary if the history &

Treatment and management

Conjunctivitis sometimes requires medical attention.

Bacterial conjunctivitis is usually treated with antibiotic eye drops or ointments that cover a broad range of bacteria (chloramphenicol or fusidic acid used in UK).

Although there is no cure for viral conjunctivitis, symptomatic relief may be achieved with cool compresses and artificial tears.

Conjunctivitis due to burns, toxic and chemical require careful wash-out with saline, especially beneath the lids, and may require topical steroids.

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