How is Conjunctivitis Diagnosed?

The conjunctiva is a layer of pink tissue that overlays the eye and the inside of each eyelid. Conjunctivitis is an inflammation of the conjunctiva, sometimes referred to as pinkeye. It is a very common eye complaint, comprising about 30% of all eye-related emergency department visits. General symptoms include redness, discharge, irritation, and light sensitivity.

Conjunctivitis can be caused by viruses, bacteria, fungi, parasites, toxins, chemicals, and allergens. Viral conjunctivitis is the most common form. Both viral and bacterial conjunctivitis are highly contagious. Most cases of conjunctivitis are self-limiting, but some may require treatment to prevent serious complications, such as corneal perforation from an infection, corneal ulcers, and dryness leading to damage of the surface of the cornea.

Diagnosis typically involves a careful history and a physical examination of the eyes. The conjunctiva may also be swabbed for culture.

Ask The Expert - Dr. Gabriel Sosne - Pink Eye and Viral Eye Infections

Evaluation of Conjunctivitis

Patients typically complain that their eyelids stick together upon waking in the morning. Other symptoms may include itching, burning, or a foreign-body sensation. Watery discharge, mucus, or pus may be present in the eyes. Some types of conjunctivitis present with light sensitivity. Recent upper respiratory infection suggests viral conjunctivitis.

Inflammation in both eyes suggests a viral or bacterial origin. Inflammation in one eye only is more likely to be due to toxic, chemical, or mechanical agents.

Bacterial Conjunctivitis

In bacterial conjunctivitis, the onset of inflammation is acute, pain is minimal, and it’s not uncommon that the patient is aware of an exposure to infection. Bacterial conjunctivitis may be secondary to ocular surface diseases like keratitis sicca, or chronic blepharitis. The most common infectious organisms in bacterial conjunctivitis are species of Staphylococcus and Streptococcus. Thick discharge is present, along with swollen conjunctivae and enlargement of the periauricular lymph nodes.

Bacterial conjunctivitis caused by chlamydia differs in that there is a history of sexually transmitted disease. Discharge is minimal. Some preauricular adenopathy (swollen lymph nodes) may be present, but typically there will not be swelling of the lymph nodes. Chlamydial conjunctivitis is often chronic, with a pattern of flaring and remitting.

Viral Conjunctivitis

Viral conjunctivitis can have acute or subacute onset, little pain, and a history of exposure. Discharge is usually watery. Extreme light sensitivity and a foreign-body sensation may be present. Preauricular lymph nodes may be enlarged. The most common virus causing conjunctivitis is adenovirus, and this form is called epidemic keratoconjunctivitis.

Another type of viral conjunctivitis called epidemic haemorrhagic conjunctivitis is caused by enterovirus 70. In that type of infection small subconjunctival haemorrhages are present. The infection lasts only a few days.

Allergic Conjunctivitis

In allergic conjunctivitis, there will be no exposure history, and the inflammation is not painful. Discharge is clear and watery, and mucus may or may not be present. There will be no swelling of the lymph nodes, but swelling of the conjunctiva is common.

Giant Papillary Conjunctivitis

Giant papillary conjunctivitis is mainly found in contact lens wearers. Symptoms include excessive itching, mucus production, and intolerance to use of contact lenses. Large papillae are visible on the upper conjunctiva when the lid is turned back.



Further Reading

Last Updated: Jun 25, 2019

Dr. Catherine Shaffer

Written by

Dr. Catherine Shaffer

Catherine Shaffer is a freelance science and health writer from Michigan. She has written for a wide variety of trade and consumer publications on life sciences topics, particularly in the area of drug discovery and development. She holds a Ph.D. in Biological Chemistry and began her career as a laboratory researcher before transitioning to science writing. She also writes and publishes fiction, and in her free time enjoys yoga, biking, and taking care of her pets.


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