Ophthalmology Red Flags in Primary Care

Eye presentations are common in primary care, but a small number represent true ophthalmic emergencies where delayed recognition can lead to permanent sight loss, neurological injury, or even death. For GP trainees and AKT candidates, the challenge is not diagnosing rare eye conditions, but rapidly identifying red‑flag features that require urgent or same‑day specialist referral.

The RCGP AKT, NICE guidance, and British Thoracic Society / Royal College–endorsed ophthalmology pathways consistently emphasise the same principle:

Most eye conditions are benign — but the few that are dangerous must not be missed.

Red Flag	Clinical Significance / Concern	Key Diagnostic Features	Referral Action
Sudden painless visual loss	CRAO/BRAO, retinal detachment, vitreous haemorrhage; stroke equivalent	Cherry-red spot (CRAO), hemifield shadow, sudden floaters ± flashes	🔴 Same-day emergency referral; initiate stroke protocol if CRAO suspected
Sudden painful visual loss	AAG, optic neuritis, anterior uveitis, keratitis	Mid-dilated pupil, corneal haze, ↑ IOP, photophobia, ciliary flush	🔴 Same-day ophthalmology referral
RAPD	Optic nerve or retinal pathology; not caused by cataracts	Swinging light test positive; asymmetric light response	⚠️ Urgent (next-day) referral
Flashes + floaters ± visual field loss	Retinal detachment or tear (sight-threatening)	Photopsia, shadow/curtain in field, ↑ floaters	🔴 Same-day referral i...

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