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Michael David Abramoff, Hrvoje Bogunovic, Young H Kwon, Brice Critser, Mona K Garvin, Milan Sonka; Repeatability of Automated OCT-based 24-2 Visual Threshold Estimationin Patients with Glaucoma. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):1696.
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© ARVO (1962-2015); The Authors (2016-present)
To determine relationships between SD-OCT derived regional damage to the retinal ganglion cell-axonal complex (RGC-AC) and visual thresholds for each location of the Humphrey 24-2 visual field, in all stages of open-angle glaucoma, and determine the repeatability of our predictive method.
Subjects with early, moderate and advanced glaucoma were recruited from a tertiary glaucoma clinic. Standard automated perimetry (SAP) Humphrey SITA 24-2 and 9-field Spectralis SD-OCT, covering 60° of retina, were acquired. In the repeatability subset, patients underwent SAP and OCT twice. Individual OCT volumes were aligned, nerve fiber (NFL), ganglion cell and inner plexiform layers (GCL+IPL) co-segmented. Layers were then partitioned into 54 sectors corresponding to the 24-2 grid. A Support Vector Machine was trained independently for each sector to predict the sector threshold, using these structural properties, of the associated RGC-AC trajectory that originates at the cell of interest, only on the non-repeatability subjects. Prediction of individual sector thresholds was compared in leave-one-out fashion to corresponding SAP thresholds using correlation R and average root mean squared error (RMSE). Repeatability was evaluated on the repeatability subset using test-retest correlation (R) and coefficient of determination (R2) across the 54 sectors without retraining.
122 consecutive subjects diagnosed with glaucoma, 43 early, 39 moderate, and 40 advanced, were included (122 eyes), as well as 20 additional subjects, 6 early, 7 moderate, and 7 advanced, into the repeatability subset. R of automated OCT-based predicted thresholds to SAP thresholds on 122 subjects was 0.68 (0.47 - 0.82), and RMSE 6.92dB (3.93 - 8.68dB) (Fig 1). OCT based prediction repeatability on 20 subjects was R=0.98 and R2=0.95 (Fig 2 left) while SAP had R=0.88 and R2=0.74 (Fig 2 right).
Predicting individual 24-2 visual field thresholds from structural information derived from 9-field SD-OCT local NFL and GCL+IPL thicknesses using the RGC-AC concept is feasible, showing the potential for the predictive ability of SD-OCT structural information for visual function, with better reproducibility than SAP SITA Humphrey 24-2. Ultimately, it may be feasible to complement and reduce the burden of subjective visual field testing in glaucoma patients with predicted function derived objectively from OCT.
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