Design: Retrospective cohort within a prospective glaucoma study (DIGS)
Population: 180 eyes of 116 patients with glaucoma or preperimetric glaucoma
Primary outcome: Timing and agreement of progression detection by OCT, OCTA and fields
Effect: OCTA lead time 2.3 years (1.3 to 3.2) over fields; specificity 68.9% vs 75.6% for OCT

This JAMA Ophthalmology analysis, published 3 September, followed 180 eyes of 116 patients from the Diagnostic Innovations in Glaucoma Study with OCT, OCT angiography and visual fields over a mean of 5.1 years.

Progression was detected in 107 eyes (59.4%) by at least one test: 32.2% by OCTA vessel density, 25.0% by OCT retinal nerve fibre layer thickness and 32.8% by visual fields. OCTA vessel density was first to detect progression in 37.4% of progressing eyes. Mean lead time before visual field progression was 2.3 years for OCTA (95% CI 1.3 to 3.2) and 1.5 years for OCT. Specificity in stable eyes was 68.9% for OCTA and 75.6% for OCT.

OCTA may give earlier warning, especially in advanced disease where OCT floors out, but at the price of more false alarms. It complements rather than replaces OCT and fields, and the cost of adding it has not been assessed.

OCT angiography vessel density detected progression earliest in more eyes than OCT or fields.
It gave a mean 2.3-year lead time over visual field progression.
Expect more false positives: specificity was about 69% against 76% for OCT.
Confirm OCTA-flagged progression with repeat testing before escalating treatment.

Why it matters

Suggests a way to see progression years earlier in patients whose fields are unreliable or whose OCT has bottomed out.

The statistics, in plain English

A specificity of 68.9% means about three in ten stable eyes would be wrongly flagged as progressing, so a single OCTA change is not enough to change treatment.