Red Eye - Differential Diagnosis Framework



What?

Redness in the eye can be caused by many conditions and injuries that can lead to irritation, blood in the eye, or swelling of blood vessels.



Common Causes:

• Conjunctivitis, corneal abrasions, etc., that usually affect superficial eye structures, lid or lashes



Dangerous Causes:

• Usually affect deeper structures like the sclera, anterior and posterior chambers, nerves, and vessels



Alarm (Emergent):

• Acute angle closure glaucoma

• Hyphema

• Hypopyon

• Bacterial keratitis

• Acute endophthalmitis

• Herpes ophthalmicus

• Orbital cellulitis

• Globe trauma

• Chemical injury



Urgent:

• Scleritis

• Herpes keratitis

• Uveitis



Time to Think:

• Conjunctivitis (most common)

• Blepharitis

• Subconjunctival hemorrhage

• Episcleritis



Ocular Emergencies Without a Red Eye:

• Optic neuritis

• Retinal detachment

• Central retinal artery occlusion

• Central retinal vein occlusion



Conjunctiva:

• Conjunctivitis (bacterial, viral, allergic)

• Episcleritis

• Scleritis (+ Photophobia)

• Hemorrhage



Lids/Lashes:

• Hordeolum

• Chalazion

• Blepharitis



Cornea:

• Abrasion (+ Photophobia)

• Contact lens overwear

• Foreign body

• Infectious keratitis (bacterial, viral)



Lens:

• Acute angle closure glaucoma



Anterior Chamber/Uvea/Iris:

• Iritis

• Hyphema

• Hypopyon

• Uveitis (+ Photophobia)

• UVEA: comprised Iris, Ciliary body, Choroid



Questions to Ask:

• Unilateral or bilateral symptoms + duration?

• Trauma?

• Discharge?

• Photophobia?

• Is the eye painful?

	• Globe rupture

	• Foreign body

	• Uveitis/Ulcer

	• Narrow angle glaucoma

	• Keratitis (Herpes keratitis, herpes zoster ophthalmicus, UV)

	• Scleritis

• Is the eye painless?

	Painless conditions include:

	• Hyphema

	• Conjunctivitis

	• Conjunctival hemorrhage

• Is there any subjective vision loss?

	Complete vision loss is very rare:

	• End stage endophthalmitis

	• Narrow angle closure glaucoma

• Is there partial visual loss or blurriness?

	• Corneal ulcer

	• Keratitis

	• Hyphema

• Contact lens use?



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