Red Eye: A Guide for Non-specialists

Abstract

Background: Red eye can arise as a manifestation of many different systemic and ophthalmological diseases. The physician whom the patient first consults for this problem is often not an ophthalmologist. A correct assessment of the urgency of the situation is vitally important for the planning of further diagnostic evaluation and treatment.

Methods: This review is based on pertinent publications retrieved by a selective literature search in PubMed in August 2016 as well as on the authors' own clinical and scientific experience.

Results: Primary care physicians typically see 4-10 patients per week who complain of ocular symptoms. Most of them have red eye as the major clinical finding. A detailed history, baseline ophthalmological tests, and accompanying manifestations can narrow down the differential diagnosis. The duration and laterality of symptoms (uni- vs. bilateral) and the intensity of pain are the main criteria allowing the differentiation of non-critical changes that can be cared for by a general practitioner from diseases calling for elective referral to an ophthalmologist and eye emergencies requiring urgent ophthalmic surgery.

Conclusion: The differential diagnosis of red eye can be narrowed down rapidly with simple baseline tests and targeted questioning. Patients with ocular emergencies should be referred to an ophthalmologist at once, as should all patients whose diagnosis is in doubt.

Figure 1

Flow diagram for classification of red eye and its most frequently occurring causes Flow diagram for differentiation and classification of causes of red eye for non-specialists. Bilateral findings often begin in one eye and affect the other eye later. “Emergency” means that immediate referral to an ophthalmologist is recommended. Figure modified from Cronau et al. (3)

Figure 2

Principal causes of unilateral acute red eye, in the absence of suspicion of foreign body/perforation

Figure 3

Chemosis Chemosis of the conjunctiva in infectious conjunctivitis

Figure 4

Subconjunctival hemorrhage The arterial blood pressure should be measured to exclude a hypertensive crisis. If trauma cannot be ruled out, ophthalmosurgical exploration is required.

Figure 5

Corneal ulcer White or gray discoloration of the cornea with an obvious tissue defect

Figure 6

Episcleritis Inflammation of the connective tissue between sclera and conjunctiva with reddening, typically confined to one sector, and distinct dilatation of the episcleral vessels

Figure 7

Scleritis Typical appearance of scleritis: diffuse, “washed-out” red eye with dilatation of deep and superficial vessels

Figure 8

Hordeolum Acute, painful bacterial inflammation of sebaceous or sweat glands at the margin of the eyelid

Figure 9

Lower-lid ectropion External rotation of the lower lid, so that the tear fluid can no longer properly moisten the ocular surface. Conjunctival hyperemia owing to lagophthalmos is the result.

Figure 10

Carotid–cavernous sinus fistula Bilateral massive dilatation of the conjunctival and episcleral vessels