- Design
- Retrospective observational two-centre study
- Population
- 80 patients with biopsy-proven GCA and 179 with NAION
- Primary outcome
- Prevalence of PAMM on OCT
- Effect
- 28% in GCA vs 0% in NAION (P < 0.001); 29% in GCA without visual symptoms
This retrospective study from two tertiary neuro-ophthalmology practices reviewed OCT scans from 80 patients with biopsy-proven giant cell arteritis and 179 with non-arteritic anterior ischaemic optic neuropathy, looking for paracentral acute middle maculopathy (PAMM) — hyperreflective bands in the middle retinal layers marking deep capillary ischaemia.
PAMM was present in 28% of patients with GCA and in none with NAION. Among those with GCA it appeared in 33% with persistent visual symptoms and, notably, in 29% with no visual symptoms at all. It was seen as often after corticosteroids had started as before (29% vs 22%), and did not track presenting acuity or field loss.
PAMM is not sensitive enough to rule GCA out, but in a patient with optic disc swelling it points firmly towards the arteritic cause. And because it persists after steroids, a scan taken a few days into treatment can still show it.
- In a patient with ischaemic optic neuropathy, look for PAMM on macular OCT.
- PAMM favours giant cell arteritis over NAION; its absence does not exclude GCA.
- Consider macular OCT in patients with suspected GCA even without visual symptoms.
- Starting steroids does not erase the sign, so a later scan remains useful.
- Never delay steroids to obtain an OCT.
Why it matters
A quick, non-invasive scan can strengthen the case for arteritis while biopsy is awaited.
Don't overread it
A retrospective two-centre series — PAMM's sensitivity is too low for it to rule GCA out.
The statistics, in plain English
PAMM in 28% of GCA means it is missed in most patients — low sensitivity. Its absence in all 179 NAION patients suggests very high specificity, but zero in one series is not proof it never occurs. The steroid comparison (OR 1.43, CI 0.41 to 4.94) is too imprecise to say steroids make no difference, only that PAMM persists.
Read the rest in the app
You have read your two free briefings this month. The app carries all 27 specialties, every morning, free — and this finding is waiting in it.
Scan to keep reading on your phone. No account needed to start.
Tomorrow morning, before your first patient
One edition a day for ophthalmology, written by the desk, every claim tied to its paper. Six minutes.
Get the app — free