Abstract
Purpose :
Precise measurement of of Bruch’s Membrane Opening – based on Minimum Rim Width (BMO-MRW), Minimum Rim Area (BMO-MRA) and peripapillary retinal nerve fiber layer thickness (RNFLT) can support detection of structural glaucomatous damage and progression. We performed a prospective clinical study to evaluate the repeatability and reproducibility (R&R) of these parameters with the Spectralis OCT (Heidelberg Engineering) for normal and glaucoma subjects.
Methods :
32 eyes of 32 subjects (12 f, 22 m, mean age 58±17 years) with manifest refraction spherical equivalent of -6D to +6D and astigmatism of < 2D were analyzed. Group 1 included normal subjects (n) with healthy eyes without prior intraocular surgery except cataract surgery and laser in situ keratomileusis and without clinically significant posterior segment diseases. Group 2 included early to advanced glaucoma eyes (g). Subjects underwent 1 baseline and 3 follow-up measurements, using the true-track eye tracking functionality on three Spectralis OCT devices in randomized order, each operated by a single operator. Outcome measures were global and sectorial averages of BMO-MRW and BMO-MRA, and of peripapillary RNFLT obtained from 3.5, 4.1 and 4.7 mm diameter circle scans aligned on the center of BMO. Coefficients of variation (COV) were calculated and a mixed-effects analysis of variance (ANOVA) was performed.
Results :
COVs of global and sectorial BMO-MRW / BMO-MRA measurement under reproducibility conditions ranged from 0.7% to 2.4% (n: 0.77 to 2.8; g: 0.64 to 3.3). Respective COVs under repeatability conditions ranged from 2.2% to 3.1% (n: 0.38 to 1.4; g: 0.78 to 2.5). The ANOVA Gage R&R of BMO-MRW / BMO-MRA measurement ranged from 0.05% to 1.1% (n: 0.1 to 2.98; g: 0.17 to 1.25). COVs of global and sectorial RNFLT measurements under reproducibility conditions ranged from 0.5% to 2.8% (n: 1.4 to 2.5; g: 1.7 to 4.1). Respective COVs under repeatability conditions ranged from 1.6% to 3.5% (n: 0.39 to 1.0; g: 0.64 to 3.6). The ANOVA Gage R&R of RNFLT measurement ranged from 0.5% to 2.7% (n: 1.7 to 8.7; g: 0.45 to 4.0).
Conclusions :
For R&R, the COVs of measured parameters were higher for glaucoma eyes compared to normal controls, while Gage R&Rs were lower. All values were within expected ranges and may be taken into account in the clinical assessment of baseline and follow-up measurement results.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.