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Meera Ramanathan, Jun Mo Lee, Nila Cirineo, Abdelmonem Afifi, Esteban Morales, Fei Yu, Kouros Nouri-Mahdavi, Anne Coleman, Joseph Caprioli; Performance of the Visual Field Index in Patients with Advanced Field Loss. Invest. Ophthalmol. Vis. Sci. 2013;54(15):3929.
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© ARVO (1962-2015); The Authors (2016-present)
The purpose of this study is to explore the relationship between the Visual Field Index (VFI) and the visual field mean deviation (MD), determined by analyzing the change in VFI (ΔVFI) with change in MD (ΔMD) in patients with advanced damage.
The MD and VFI values obtained from visual field tests conducted on 176 eyes of 168 glaucoma patients having an MD around -20dB were studied. A total of 535 exams from 1984 to 2011 with MD values within the range of -16dB to -24dB were included. Two divisions were made with the first having serial MDs all less than or greater than -20 dB and the second with serial MDs crossing -20 dB. The relationship of ΔVFI with ΔMD was evaluated.
The means (±SD) for the ΔVFI are 6.47 (±9.17) corresponding to MDs on either side of -20dB and 15.41 (±7.64) corresponding to MDs crossing -20dB (p<0.0001). For ΔVFI/ΔMD, these values are 6.47 (±9.17) when the range of MD falls on either side of -20 dB, and 8.12 (±6.78) when the range of MD crosses the -20 dB value (p<0.00026).
The value of the VFI becomes highly variable with MDs crossing -20dB in comparison to those VFIs corresponding to MDs on either side of -20dB. The reason for this effect is the change from use of pattern deviation to total deviation values in calculation of VFI at the MD boundary of -20dB. The development of methods to measure visual field rates that are free from this boundary effect would be desirable.
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