5 min read
The red eye
Distinguishing conjunctival, corneal, scleral, and intraocular causes at the slit lamp.
Learning objectives
- Triage the red eye by pain, vision, and photophobia.
- Use the pattern of redness to localize the problem.
- Recognize the sight-threatening causes that cannot be missed.
1. Ask the three questions
Is there pain, reduced vision, or photophobia? Any 'yes' raises concern for a serious cause.
2. Pattern of injection
Diffuse (conjunctivitis), ciliary flush around the limbus (keratitis/uveitis), or sectoral (episcleritis/scleritis).
3. Cornea
Stain with fluorescein for abrasion, ulcer, or dendrite. A hazy cornea suggests oedema or infiltrate.
4. Anterior chamber
Cells and flare suggest uveitis; hypopyon or hyphema demands urgent attention.
Pearls
- Photophobia that improves with a topical anaesthetic points to a corneal (surface) cause.
- A fixed mid-dilated pupil with a hard, painful red eye is angle-closure until proven otherwise.