The study was done to establish a comparison of repeatability of peripapillary perfusion density and flux index measurements on referenced and non-referenced optical microangiography (OMAG) scans in normal, glaucoma suspect and glaucoma eyes.

48 eyes from 33 subjects underwent three repeat, non-referenced peripapillary OMAG scans in the same session and 43 eyes (25 subjects) underwent three referenced peripapillary OMAG scans. In the referenced scan group, repeat scans were acquired exactly on the baseline scan using the ‘track to prior scan’ option on the device. Repeatability estimates of the mean and four-sector OMAG measurements on the non-referenced and referenced scans were assessed using within-subject coefficient of repeatability (CRw) and variation (CVw).

CRw (%) of peripapillary perfusion density measurements (range: 2.0–4.1) on non-referenced scans were significantly higher than that on referenced scans (range: 1.4–2.7). CVw (%) on non-referenced and referenced scans ranged from 1.7 to 3.1 and from 1.2 to 2.1, respectively . CRw of flux index on non-referenced and referenced scans ranged from 4.4 to 5.8 and from 3.6 to 4.8, respectively. CVw on non-referenced and referenced scans ranged from 4.1 to 5.2 and from 3.3 to 4.5, respectively.

The study concluded that the repeatability estimates of OMAG measurements were better on referenced scans compared with non-referenced scans.

Reference: https://bjo.bmj.com/content/early/2020/09/21/bjophthalmol-2020-316480