How Doctors Diagnose Red Eye: What Tests Are Involved?
Published: Aug 11, 2024
Ever wondered how doctors figure out what's causing your red eye? Learn about the diagnostic tests that help pinpoint the problem.
Contents
Evaluating Visual Acuity
One of the first steps in diagnosing red eye is checking your visual acuity. Doctors use a Snellen chart to measure how well you can see at a distance. This test helps determine if your red eye is affecting your vision, which can be a sign of a more serious condition. If vision is impaired, further tests may be needed.
Penlight Examination
A penlight examination is a simple yet effective test to assess the front part of the eye. The doctor will check pupil reactions, look for discharge, and examine the pattern of redness. This examination helps differentiate between conditions like conjunctivitis and more serious issues like glaucoma. It's a quick way to gather crucial information about your eye health.

Fluorescein Staining Test
Fluorescein staining involves applying a special dye to the surface of your eye. The dye highlights any damage to the cornea, such as scratches or infections. This test is particularly useful for identifying conditions like corneal abrasions or infectious keratitis. It's a painless procedure that provides valuable insights into the cause of your red eye.
Frequently Asked Questions
A tool used to measure how well you can see at a distance.
It assesses pupil reactions and the pattern of redness to identify conditions.
It highlights corneal damage like scratches or infections.
The Bottom Line
Understanding these tests can help you appreciate the diagnostic process of red eye.
References
- Leibowitz HM. The red eye. N Engl J Med 2000; 343:345.
- Ho CS, Avery AJ, Livingstone IAT, Ting DSJ. Virtual consultation for red eye. BMJ 2021; 373:n1490.
This article has been reviewed for accuracy by one of the licensed medical doctors working for Doctronic. Always discuss health information with your healthcare provider.
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