Question 1

What are the key features distinguishing acute angle-closure glaucoma from other causes of red eye?

Accepted Answer

Acute angle-closure glaucoma (AACG) is an ophthalmic emergency. Key distinguishing features: Severe unilateral eye pain often radiating to forehead; Nausea and vomiting (can mimic acute abdomen or migraine); Fixed, mid-dilated pupil (4–6 mm) — does not constrict to light; Markedly elevated IOP (>40 mmHg, normal <21 mmHg); Cloudy or hazy cornea (corneal oedema); Reduced visual acuity; Seeing halos around lights. Systemic symptoms (headache, vomiting) can distract from the eye. Risk factors: Hyperopia (long-sighted), female, Asian ethnicity, age >60, family history. GP action: Same-day emergency ophthalmology referral — call the on-call ophthalmologist. Give IV acetazolamide 500 mg while awaiting transfer if available and no contraindication.

Question 2

When should a GP refer a patient with sudden painless vision loss as an emergency?

Accepted Answer

Sudden painless vision loss requires same-day emergency ophthalmology referral in all cases. Key causes: Central Retinal Artery Occlusion (CRAO) — sudden painless monocular blindness, cherry-red spot on fundus; Central Retinal Vein Occlusion (CRVO) — sudden vision loss, flame haemorrhages on fundus; Retinal Detachment — sudden flashes, floaters, shadow or curtain over visual field; Vitreous Haemorrhage — sudden floaters, blurred or reduced vision; Giant Cell Arteritis (GCA/Temporal Arteritis) — sudden vision loss in over 50s with headache, jaw claudication, scalp tenderness, raised ESR/CRP — start prednisolone 60–80 mg immediately (before biopsy if GCA suspected — do not delay steroids waiting for ESR). Time-sensitive: CRAO may benefit from treatment within 4.5 hours. GCA: immediate steroids prevent second eye involvement.

Feature	Conjunctivitis	Uveitis	Acute Glaucoma	Scleritis
Pain	Gritty	Deep aching	Severe	Boring, nocturnal
Vision	Normal	↓ + photophobia	Acutely ↓↓	Usually normal
Pupil	Normal	Small, irregular	Fixed, mid-dilated	Normal
Discharge	Yes (variable)	None	None	None
IOP	Normal	Normal/low	Very high (>40)	Normal
Injection	Diffuse	Ciliary (perilimbal)	Diffuse + hazy cornea	Deep, violaceous

Ophthalmology

Red Eye

Key Distinguishing Features at a Glance