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M. Fingeret, M. Verghese, L. Torres; Visual Field Progression Using Glaucoma Progression Analysis (GPA) . Invest. Ophthalmol. Vis. Sci. 2006;47(13):4001.
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© ARVO (1962-2015); The Authors (2016-present)
While a number of scoring systems have been devised to detect visual field progression in clinical trials, there has been no accepted tool for clinical care. The Glaucoma Progression Analysis (GPA) software for the HFA II perimeter (Carl Zeiss Meditec, Dublin, CA) uses empirically–determined significance limits for the variability in glaucomatous fields. Test point locations are flagged whenever change from baseline exceeds the variability in 95% of glaucomas. The pattern of significantly changing test points is evaluated using criteria from the Early Manifest Glaucoma Trial (EMGT). The analysis is based upon confirmation of change, and uses two flags to note progression: three points on two successive fields (possible progression) and three points on three fields (likely progression)
We performed a pilot study to determine the frequency which the GPA analysis suggested progression. Consecutive patients having a diagnosis of open angle glaucoma with at least five reliable visual fields done over a five–year period were eligible (6.4 MD +/– 2.3 SD). 51 patients (94 eyes) were enrolled with average age of 69.7 years SD +/–9.22.
77.66% of the group showed no progression, 12.77% were flagged as possible progression and 9.57% were classified as likely progression. The group that showed progression had larger cupping (C/D .66 vs .52) than the no progression group, and were older (71.8 vs. 70.0). The central corneal thickness was similar in all groups and not a factor in determining progression (537 um in no progression vs. 553um in progression group)
The EMGT found 45% in the treatment arm showed progression. Our study found fewer individuals (22.34%) progressing in a similar time period. The differences may be due to the type of patients enrolled, glaucoma staging, medications used, or other factors. Our results suggest that the GPA criterion for likely progression is at least 92.6% specific over a five–test sample. The monitoring for progression with perimetry is an important part of the evaluation. The GPA is a new tool that may be useful to recognize progression as opposed to variability. This study presents rates of progression occurring within a glaucomatous population.
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