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Abstract #70670 Published in IGR 18-2
Estimating OCT Structural Measurement Floors to Improve Detection of Progression In Advanced Glaucoma
Bowd C; Zangwill LM; Weinreb RN; Medeiros FA; Belghith AAmerican Journal of Ophthalmology 2017; 175: 37-44
PURPOSE: "Floor effects" in retinal imaging are defined as the points at which no further structural loss can be detected. We estimated the measurement floors for spectral-domain optical coherence tomography (SD-OCT) measurements and compared global change over time in advanced glaucoma eyes. DESIGN: Validity study to investigate measurement floors. METHODS: A longitudinal "Variability Group" of 41 eyes with moderate to advanced glaucoma (SAP MD ≤ -8 dB) was used to estimate measurement floors. Minimum rim width (MRW), ganglion cell-inner plexiform layer thickness (GC-IPLT) and circumpapillary retinal nerve fiber layer thickness (cpRNFLT) were determined. Floors were defined as the average image area with a loss < 1(st) percentile confidence interval of the variability in this group. Global rate of change and percentage of the region of interest that did not reach the measurement floor at baseline were calculated in 87 eyes with advanced glaucoma (SAP MD ≤ -12 dB). RESULTS: Global change over time in longitudinal eyes was -1.51 μm/year for MRW, -0.21 μm/year for GC-IPL and -0.36 μm/year cpRNFL (all p≤0.03). The percentage of region of interest that did not reach the floor at baseline was 19% for MRW, 36% for GC-IPLT and 14% for cpRNFLT. Average (±S.D.) floors were 105 μm (±15.9 μm) for MRW, 38 μm (±3.4 μm) for GC-IPLT and 38 μm (±4.2 μm) for cpRNFLT. CONCLUSIONS: In advanced glaucoma, more GC-IPL tissue remains above the measurement floor compared to other measurements, suggesting GC-IPL thickness is the better candidate for detecting progression. Progression in SD-OCT measurements is observable in advanced disease.
Hamilton Glaucoma Center, Department of Ophthalmology and Shiley Eye Institute, University of California, San Diego, La Jolla, CA 92093-0946.
Full articleClassification:
6.9.2.2 Posterior (Part of: 6 Clinical examination methods > 6.9 Computerized image analysis > 6.9.2 Optical coherence tomography)
6.20 Progression (Part of: 6 Clinical examination methods)
