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Updated: Mar 2, 2026
In Vivo Confocal Microscopy in the Diagnosis and Management of Dry Eye: A Focus on Imaging Protocols and Interpretation
Published on: November 11, 2025
Red Eye: A Guide for Non-specialists
Andreas Frings1, Gerd Geerling, Marc Schargus
1Department of Ophthalmology, Düsseldorf University Hospital; Ophthalmological Medical Center Schweinfurt, Eye Hospital Schweinfurt Gerolzhofen.
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.
