eTable 2. Classification of the causes of red eye by disease site.
| Characteristics | Intraocular diseases | Diseases of the ocular adnexa | ||
|
Iritis/ iridocyclitis |
Acute angle-closure glaucoma |
Hordeolum |
Carotid–cavernous sinus fistula |
|
| Incidence | – | – | ++ | – |
| (U)nilateral/ (B)ilateral |
U | U | U | U |
| Worsening of vision |
++ | +++ | (+) | + |
| Photophobia | ++ | ++ | – | – |
| (L)ocalized/ (D)iffuse reddening |
D | D | + | D |
| (S)uperficial/ (D)eep reddening |
S/D | S/D | Eyelid | D |
| Secretion: (P)urulent/ (W)atery/ (M)ucinous |
– | – | P | – |
| Conjunctival hemorrhage |
– | – | – | – |
| Conjunctival chemosis |
(+) | – | – | (+) |
| Corneal lesions | – | + | – | – |
| Foreign body event |
– | – | – | – |
| Elevated ocular pressure |
– | +++ | – | + |
| Further features | Rheumatic underlying disease | Halos, extreme pain, flattened anterior chamber, opaque cornea, unresponsive pupil; NB: general symptoms | Localized reddening and swelling of the eyelids | Conjunctival tortuosity, headache, rushing sound, pulsatile exophthalmos |
| Urgency of definitive diagnosis | Urgent referral to ophthalmologist | Emergency, immediate referral to eye surgery center | Normal referral to ophthalmologist | Urgent referral to ophthalmologist |
Incidence: +++ very often, ++ often, + occasionally, – rarely
Remainder of table: (+) may occur, +/– can occur with or without changes