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B. M. Bengtsson, A. Heijl; Prediction of Glaucomatous Visual Field Loss by Extrapolation of Linear Trends. Invest. Ophthalmol. Vis. Sci. 2008;49(13):1106.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate how well linear analysis of visual field trends, based on the new global Visual Field Index (VFI), can predict future visual field loss.
Glaucoma patients with long series including 10 fields or more of SITA Standard visual field tests were eligible for incusion. For each series VFI was regressed over time for the first 5 years, then the 5 years linear slope was extrapolated to the time of the last test and a predicted VFI value (VFI5) was calculated. A second analysis regressing VFI over time including all tests in each series was performed to estimate VFI at the time for the last test (VFIall) (interpolation). The predicted VFIs based on the 5 initial field tests were compared to the estimated VFIs based on all tests by letting VFI5 explain VFIall in a linear regression analysis.
Fifty eyes of 50 consecutively selected patients were included. Mean age was 70 years (50 - 89). The mean number of tests per series was 12, (10 - 16). Twelve eyes (24%) had undergone cataract surgery during follow-up. The comparison between predicted and estimated regression VFIs was highly significant (p<0.0001), the average change in estimated VFIall was 0.9 % for each 1% in change of predicted VFI5. The coefficient of determination, r2, was 0.75, i.e. 75% of the variation in estimated VFIall was explained by the variation in predicted VFI5.
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