The Red Eye: Keratitis, Conjunctivitis, Episcleritis, Scleritis, Pterygium/Pinguecula

The Red Eye: Keratitis, Conjunctivitis, Episcleritis, Scleritis, Pterygium/Pinguecula

David Peak

Neha Shaik


The etiology of the red eye includes the spectrum from nonemergent conditions to potentially sight-threatening true emergencies. The terminology can be challenging because some terms such as conjunctivitis and keratitis merely refer to pathology of a particular part of the eye, but the clinician must infer the cause of the pathology in order to effectively treat the patient. Inciting pathology can also affect multiple parts of the eye simultaneously and be related to infection, toxins, trauma, or inflammatory conditions. An understanding of the various conditions will help inform the urgency of ophthalmology consultation or follow-up.


The approach to the history and exam for the red eye is somewhat straightforward given that, except for isolated posterior scleritis, all the associated conditions will have abnormalities on physical examination. Important features of the history include timing, associated features, and exacerbating features. In addition to the ocular examination, inspection of the head, face, and neck for abnormalities, including swelling, erythema, rash, trauma, or infection, should be performed. A neurologic exam including visual acuity, extraocular muscle function, and visual field testing is helpful to exclude other causes. The slit-lamp examination allows an examination of the eye with magnification. Whenever pain or visual impairment is present, measuring intraocular pressure is essential. The use of fluorescein staining is helpful to identify corneal abrasions and other epithelial changes, such as dendritic lesions or punctate epithelial erosions.


In most of the red eye conditions, there will be some degree of conjunctival injection, making the history and exam critical to rule out other etiologies. In isolated conjunctivitis, patients may describe watery, serous, or purulent discharge with crusting around the eyelids in the morning. Usually, there are minimal vision complaints. The patient may report a history of recent exposure to sick contacts or recent travel history. If both eyes are involved, usually one eye developed symptoms first. Upper respiratory symptoms may indicate a viral etiology.

Allergic conjunctivitis is usually bilateral, symmetric, and characterized by itching and tearing. The exam will demonstrate a diffusely injected red eye or eyes (including both the bulbar and palpebral conjunctiva). The eyelids may be swollen, and discharge may be apparent (Figure 36.1).

Purulent discharge may indicate a bacterial etiology or epidemic keratoconjunctivitis (EKC), a severe and highly contagious adenoviral infection. In cases of copious discharge, gonococcal or
chlamydial conjunctivitis should also be considered. In addition to examination of the eyes, palpable preauricular lymph nodes may also support the diagnosis of EKC.

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Nov 11, 2022 | Posted by in EMERGENCY MEDICINE | Comments Off on The Red Eye: Keratitis, Conjunctivitis, Episcleritis, Scleritis, Pterygium/Pinguecula

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