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Visual field ‘sum of slopes’ can predict VF progression
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A visual field index called the sum of slopes can be used to estimate the probability of visual field worsening, according to a group of researchers.
Kouros Nouri-Mahdavi and colleagues at the Jules Stein Eye Institute analyzed data from 161 participants in the Advanced Glaucoma Intervention Study to determine the probability of future glaucomatous visual field progression using clinical and perimetric data. Patients enrolled in the AGIS trial and chosen for this study had at least 8 years of follow-up and a baseline visual field score of less than 16. Visual field progression at 8 years was determined with point-wise linear regression (PLR) analysis.
The course of VF progression over the first 4 years was quantified by an index, the sum of slopes, which was derived from the sum of all slopes of VF thresholds with P < 0.05 when PRL was performed on 4-year data.
After 8 years, 64 eyes (40%) progressed as determined by PLR analysis. Two parameters emerged as predictive of subsequent visual field progression: a more negative sum of slopes (that is, a faster or more extensive deterioration), and older age at the 4-year mark. When the sum of slopes alone was used to predict outcomes, it had the same predictive power
The study is published in the December issue of Investigative Ophthalmology & Visual Science.