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The Red Eye: An Intro to Conjunctivitis
Amy Patel, PA-C
The red eye is a common complaint seen in the pediatric and adult population. The most common cause of a red eye is conjunctivitis or inflammation of the conjunctiva. Anatomically, the conjunctiva is composed of two parts: palpebral and bulbar. The palpebral layer, also known as the tarsal conjunctiva, lines the inside of the eyelids while the bulbar layer covers the globe over the visible aspect of the sclera.
The diagnosis of conjunctivitis is typically due to three causes: viral, bacterial, or allergic. Diagnosis is commonly based on history, symptoms, and physical exam findings although cultures may also be ordered in more serious or refractory cases.
Bacterial Conjunctivitis
Bacterial conjunctivitis typically starts unilaterally however as it is highly contagious, may spread to the other eye over time. It typically involves purulent discharge that reaccumulates quickly, eye redness, matting of eyelids, and chemosis, which is noted with actual swelling or edema of the membrane. Common organisms that cause bacterial conjunctivitis include Staph aureus, Streptococcus pneumoniae, Haemophilus influenzae, Neisseria gonorrhoeae, and Chlamydia trachomatis. Although approximately 60% of bacterial conjunctivitis is self limiting within 1 to 2 weeks, antibiotics are usually prescribed as they reduce the duration of the disease. Broad spectrum topical antibiotics are also prescribed based on cost, suspected pathogen, allergies, product availability, and use of contact lens. Examples include ciprofloxacin, gentamicin, erythromycin, or sulfacetamide drops.
It is important to note that all contact lens users should be directed to immediately remove their contacts and avoid contact use until infection completely clears. Contact lens users have a high chance of developing ulcerative keratitis. Likewise, these patients will typically present with severe eye pain, a foreign body sensation, and photophobia. The treatment must include fluoroquinolone drops to treat for a Pseudomonas infection. Dangers of developing this include ocular ulcers and perforation and thus prompt treatment and referral to ophthalmology is essential. Other special considerations include treatment for suspected gonococcal or chlamydial conjunctivitis in sexually active patients. Cultures, prompt treatment, and referral to ophthalmology should be performed.
Chlamydial conjunctivitis is treated with systemic antibiotics such as doxycycline or azithromycin +/- topical antibiotics. Consider treating these patients for gonorrheal infection with ceftriaxone unless this has been eliminated as a potential cause. Gonococcal conjunctivitis should be treated with topical antibiotics in addition to intramuscular ceftriaxone.
Viral Conjunctivitis
Viral conjunctivitis is most commonly caused by adenovirus. It is often spread in schools or workplaces and is highly contagious. Symptoms of viral conjunctivitis include a red eye, watery discharge, tender preauricular node, conjunctival swelling, and photophobia. Patients also report a gritty or foreign body sensation in the eye. It is often bilateral but may start in one eye with later onset in the other eye. It is also common to have an upper respiratory infection concomitantly. Treatment is supportive and antibiotics are not recommended. Special considerations when diagnosing viral conjunctivitis include infection by herpes zoster or herpes simplex. Conjunctivitis in these cases may advance to keratitis and therefore require close ophthalmology follow up.
Zoster patients will often have herpetiform or vesicular lesions in the distribution of the 5th cranial nerve. You may be able to identify dendritic lesions on fluorescein stain exam. Symptoms include eye pain, photophobia, preauricular lymphadenopathy, and visual changes. Treatment for zoster includes oral antivirals such as acyclovir and urgent ophthalmology follow up. Avoid topical corticosteroid use as it may potentiate the herpes virus.
Allergic Conjunctivitis
Allergic conjunctivitis involves bilateral eye redness, pruritus, injection, lid swelling, and watery eye discharge. Common allergens include pollen, animal dander, and environmental exposures. Allergic conjunctivitis does not cause matting of the eyes or eye pain. Symptoms are typically worse in the spring and summer when environmental allergies are at its peak. Treatment of allergic conjunctivitis varies depending on cause and may include cool compresses, artificial tears, antihistamines, decongestants, or mast cell stabilizers. Follow up recommendations include both ophthalmology as well as an allergist to determine the underlying cause. In severe cases of allergic conjunctivitis, topical corticosteroids are prescribed but should only be done by ophthalmology.
A thorough history is key in differentiating between bacterial, viral, and allergic conjunctivitis as there is no single symptom to clearly distinguish one from the other. In treatment summary, bacterial conjunctivitis, although usually self-limiting, is treated with topical antibiotics. Viral conjunctivitis is supportive unless herpetic infection is involved. Allergic conjunctivitis is treated with cool compresses, lubricants, and antihistamines. If loss of vision or photophobia is a concern, refer to ophthalmology urgently.
References
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Azari AA, Barney NP. Conjunctivitis: A Systematic Review of Diagnosis and Treatment. JAMA.2013;310(16):1721–1730. doi:10.1001/jama.2013.280318
Jacobs MD, Deborah. Conjunctivitis. Post TW, ed. UpToDate. Waltham, MA: UpToDate Inc. http://www.uptodate.com. Accessed on October 10, 2022.
Morrow, G. L. (1998, February 15). Conjunctivitis. American Academy of Family Physicians. https://www.aafp.org/pubs/afp/issues/1998/0215/p735.html
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