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Marina C. Sousa, Pilar A. Moreno, Luis Gustavo Biteli, Gabriela C. Barretto, Tiago S. Prata; The New Visual Field Index: Correlation With Conventional Perimetric Indices In Different Stages Of Glaucoma. Invest. Ophthalmol. Vis. Sci. 2011;52(14):5507.
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© ARVO (1962-2015); The Authors (2016-present)
We investigated the correlation between 2 well-established [mean deviation (MD) and pattern standard deviation (PSD)] and one new [visual field index (VFI)] perimetric index in patients with different stages of primary open angle glaucoma (POAG).
We prospectively enrolled POAG patients (glaucomatous optic neuropathy and reproducible VF defect) and glaucoma suspects (ocular hypertension) with previous experience in visual field (VF) testing (≥ 3 exams) from May 2010 to September 2010. Those with any ocular disease other than glaucoma were excluded. All patients underwent achromatic standard automated perimetry (SAP). Tests with unreliable results were not included in the analysis. We investigated the correlation between the 3 perimetric indices and their behavior in different stages of the disease.
One hundred and two eyes of 68 patients (mean age, 60.8±14.2 years) were included. Average values for MD, PSD and VFI were -7.39±8.6dB, 4.4±3.4dB and 80.8±27.8%, respectively. A strong and positive association was found between MD and VFI values (R2=0.98, P<0.001), showing a 3.2% reduction in the VFI for each dB loss in the MD index. There were significant and nonlinear correlations between VFI and PSD (R2=0.85) and MD and PSD values (R2=0.71; P<0.001). Higher PSD values were found with increasing visual field damage (as determined by MD or VFI). This initial trend was reversed with further functional damage (eyes with MD<-17dB or VFI<50%, approximately).
Despite being a new perimetric index based largely on points identified as abnormal in the pattern deviation plot, the VFI has almost perfect linear correlation with the well-established MD, behaving very similarly along the different stages of POAG. The usefulness of the PSD index is limited in patients with very advanced glaucoma, as it tends to "normalize" in these cases.
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