The “red eye” is a common presenting symptom in primary care, spanning a spectrum of conditions from benign to sight-threatening emergencies. Knowing how to differentiate these conditions quickly is key to providing safe, effective care.
Red Eye Fast Facts
- What causes red eye? Inflammation in any part of the eye can lead to redness. Understanding where the inflammation originates will help you narrow the differential.
- When to worry? While most cases are benign, emergent causes—though rare—require immediate attention to prevent vision loss.
- Where to start? A systematic approach using the CARE mnemonic—Common, Atypical, Rare, Emergent—can help you categorize red eye cases and decide when to refer or manage in the clinic.
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Common |
These conditions are typically non-emergent and manageable in an ambulatory setting:
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Atypical |
Occasionally, red eye can result from non-ocular causes:
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Rare |
Emergent causes are also thankfully rare, so we will lump these causes with emergent. |
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Emergent Causes of Red Eye |
These conditions are sight-threatening and require emergent (dial the phone right now!) ophthalmology referral:
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Red eye is a frequent complaint in primary care, with differential diagnoses ranging from minor, self-limiting conditions to rare, sight-threatening emergencies. A systematic approach using the CARE mnemonic can help guide clinical decision-making. Most cases, such as conjunctivitis, dry eye syndrome, or corneal abrasions, are manageable in outpatient settings, while emergent conditions like acute angle-closure glaucoma, orbital cellulitis, or chemical burns require immediate referral to prevent vision loss. Key red flags to remember for emergent causes include severe pain, vision changes, photophobia, and unilateral redness with proptosis. By staying vigilant and methodical, you can ensure safe, effective care for patients presenting with red eye.
