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Alberto Diniz-Filho, Linda M Zangwill, Akram Belghith, Robert N Weinreb, Felipe A Medeiros; Progression in Glaucoma Suspects is Detected Earlier with Imaging than Standard Automated Perimetry. Invest. Ophthalmol. Vis. Sci. 2016;57(12):353.
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© ARVO (1962-2015); The Authors (2016-present)
To estimate the time to detect progression in glaucoma suspects followed over time with spectral-domain optical coherence tomography (SDOCT) and standard automated perimetry (SAP).
This was a prospective observational cohort study involving 376 eyes of 250 patients suspected of having glaucoma. All eyes had normal SAP results at baseline and were followed for an average of 4.6 ± 1.1 years with an average of 8.7 ± 3.2 SAP and SDOCT tests. Ordinary least squares linear regression (OLS) models were used to regress SAP mean deviation (MD) and SDOCT (Spectralis, Heidelberg Engineering, Dossenheim, Germany) average retinal nerve fiber layer thickness (RNFL) values over time for each eye. Residuals were extracted from OLS regression to represent the expected variability estimates for levels of SAP MD and RNFL thickness. Distributions of residuals were then obtained for each level of MD or RNFL thickness in the population. These distributions allowed reconstruction of SAP MD and SDOCT average RNFL thickness trajectories over time by computer simulation, according to expected “true” rates of glaucoma progression. 100,000 tests were then simulated for SAP and SDOCT under different assumptions about rate of change and frequency of testing. Empirical cumulative distribution functions (CDF) were built to investigate the probability of detecting progression (i.e., statistically significant slope) over time.
Average SAP MD at baseline was -0.48 ± 1.4 dB, whereas SDOCT average RNFL thickness was 89.3 ± 12.2 μm. Median absolute residuals were 0.51 dB (IQR: 0.23 –0.78) and 1.15 μm (IQR: 0.57 – 2.78) for SAP MD and SDOCT average RNFL thickness, respectively. When simulations were performed assuming true rates of progression of -0.75 μm/year and -0.13 dB/year (average rates of change in the cohort) and 6-month testing interval, the median time to detect progression was significantly earlier with SDOCT than SAP (mean difference=3.55 years; P<0.01, Figure). At 8 years of follow-up, 82% of patients would have been detected as progressing by SDOCT versus 40% on SAP.
When trend-based methods are used to evaluate change in global indices of structure and function, detection of progression is seen significantly earlier with SDOCT than SAP.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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