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D. A. Mock, A. Coleman, A. Afifi, E. Bitrian, F. Yu, K. Nouri-Madhavi, Y. Shaikh, J. Caprioli; Discrimination of Fast and Slow Components of Visual Field Changes in Glaucoma. Invest. Ophthalmol. Vis. Sci. 2010;51(13):5502.
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© ARVO (1962-2015); The Authors (2016-present)
To establish mathematical models, insensitive to the diffuse effects due to cataracts, that statistically discriminate fast from slow regional rates of progressionfrom glaucoma in visual field series.
We analyzed longitudinal visual field (VF) series (SAP 24-2) in pseudophakic patients treated for primary-open angle glaucoma with progressive glaucoma (POAG) and phakic patients with no glaucomatous damage but progressive cataract (CAT). Progression rates are calculated with an exponentially fitted model. From previously archived VF databases with known patterns of progression, we developed algorithms that differentiate fast from slow regions of progression. A regression-based cluster analysis of the progression rates checked the model for relevance with prior knowledge. We used maximally ranked statistics, adjusted with multiple testing, that provided field-dependent cutoffs that partition the rates into fast and slow clusters. The cutoffs were determined by finding the minimum p-value that was generated under an adjusted statistical test for each possible subgroup of ranked rates (min size=3). The mean was then calculated for the partitioned subgroups. With the same procedure, we compared the progression rates in POAG and CAT patients.
The distribution of differences between fast and slow regional rates is statistically different between POAG [n= 67, mean follow-up time=8.3 yrs, mean difference fast&slow=0.23 dB/yr, sd=0.12, kurtosis= -0.25] and CAT [n=20, mean follow-up=7.4 yrs, mean difference fast&slow=0.11 dB/yr, sd=.10, kurtosis=2.5], unpaired t-test p<.00001.
The regional progression rates in CAT are more homogeneous and the regional progression rates in POAG are more heterogeneous. This approach may be a useful method to help separate the components of glaucomatous and cataractous visual field change in patients with glaucoma and provide specific regional rates of deterioration from glaucoma.
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