Frequency of Agreement Between Structural and Functional Glaucoma Testing: A Longitudinal Study of 3D OCT and Current Clinical Tests.

Purpose: To evaluate how often tests of structure and function detect glaucoma progression at the same study visit. Tests include current glaucoma clinical tests and a new 3-dimensional (3D) optical coherence tomography (OCT) rim measurement.

Design: Prospective cohort study.

Methods: For 124 open-angle glaucoma patients at a single institution, one eye was randomly selected for each patient. Patients were included if they had open-angle glaucoma and if they had at least 4 yearly study visits. Study visits included a full dilated eye exam, disc photography (DP), Humphrey visual field (HVF 24-2) testing, 2D OCT retinal nerve fibre layer (RNFL) thickness measurements, and 3D OCT neuroretinal rim measurements (i.e., minimum distance band or MDB). For each test at each study visit, eyes were classified as progressors or non-progressors using event-based analysis. Agreement occurred if tests progressed in the same eye at the same study visit. Agreements between all compared tests were calculated as percentages of agreement.

Results: The study included 124 open-angle glaucoma eyes, which had an average follow-up period of 66.9 ± 16.4 months. Structural tests (i.e., DP, global RNFL thickness, and global MDB rim thickness) progressed at the same visit as the functional test (i.e., HVF testing) in only 5.0% (3/60) to 16.0% (13/81) of eyes. Global MDB thickness and global RNFL thickness showed similar agreement with functional HVF testing (i.e., 16.0% [13/81] and 8.3% [7/84], respectively), and global MDB thickness showed better structure-function agreement with HVF testing than between DP and HVF testing (i.e., 5.0% [3/60], P = 0.04). For all paired comparisons between testing methods, eyes with moderate glaucoma showed similar or better agreement than eyes with mild or severe glaucoma.

Conclusions: Clinical tests of structure and function do not usually progress at the same clinic visit. Most of the time, glaucoma progression is only detected by one or two tests.