Abstract
Purpose :
Optical coherence tomography (OCT) provides clinicians with multiple parameters for detecting glaucoma, including the macular ganglion cell layer thickness (GCLT), peripapillary retinal nerve fibre layer thickness (RNFLT), and Bruch membrane opening (BMO) minimum rim width (MRW). It remains equivocal, however, whether one parameter is diagnostically more sensitive and whether some cases are uniquely identified by a single parameter. To address these questions, we conducted a retrospective study in a large clinical glaucoma population.
Methods :
The reference standard for glaucomatous damage was a 24-2 visual field test with an abnormal glaucoma hemifield test and either an abnormal mean deviation or pattern standard deviation at P < 5%. All patients underwent OCT imaging (Spectralis, Heidelberg Engineering) of the GCLT, RNFLT, and MRW with respect to their fovea-to-BMO axis. Each parameter was computed globally and in 6 sectors. An OCT parameter was considered abnormal if the global or any sectoral value was outside normal limits (P < 0.01) compared to age- and BMO area-adjusted normative values. The primary outcome measure was the sensitivity of each OCT parameter in diagnosing glaucoma. Comparisons between parameters were performed with the McNemar test.
Results :
This study included 721 eyes of 721 patients with glaucoma. The median (interquartile range) age was 70.7 (63.2-78.1) years and visual field mean deviation was -4.56 (-8.46 to -2.15) dB. The OCT parameter with the highest diagnostic sensitivity for glaucoma was RNFLT at 78% (95% confidence interval, 75-81%), followed by MRW at 64% (60-67%) and GCLT at 60% (57-64%). The RNFLT had statistically significantly greater sensitivity compared to the other parameters (P<0.001), while the sensitivity of MRW and GCLT were similar (P = 0.09). Of all eyes, 339 (47%) were identified by all 3 parameters. The number of cases uniquely identified by a single parameter was 30 (4%) by GCLT, 66 (9%) by RNFLT, and 17 (2%) by MRW.
Conclusions :
RNFLT had higher diagnostic sensitivity than MRW and GCLT in identifying glaucoma. However, 113 (15%) patients were uniquely identified by one of the three parameters, suggesting the clinical value of evaluating all three OCT parameters.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.