There are many possible causes of a red eye. It is important to be able to recognise the causes which require urgent referral to an ophthalmologist. Below is a brief summary of the key distinguishing features
Acute angle closure glaucoma
- severe pain (may be ocular or headache)
- decreased visual acuity, patient sees haloes
- semi-dilated pupil
- hazy cornea
- acute onset
- pain
- blurred vision and photophobia
- small, fixed oval pupil, ciliary flush
Scleritis
- severe pain (may be worse on movement) and tenderness
- may be underlying autoimmune disease e.g. rheumatoid arthritis
Conjunctivitis
- purulent discharge if bacterial, clear discharge if viral
Subconjunctival haemorrhage
- history of trauma or coughing bouts
Endophthalmitis
- typically red eye, pain and visual loss following intraocular surgery