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H. Pham, D. C. Gritz, S. R. Krishnadas, C. A. Johnson, S. L. Mansberger; Frequency Doubling Technology Perimetry Repeatability in a Developing Country. Invest. Ophthalmol. Vis. Sci. 2008;49(13):1084. doi: https://doi.org/.
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To determine the repeatability of Frequency Doubling Technology (FDT) perimetry over a long-term period in a rural location of a developing nation.
We defined a screening failure as one area of abnormal sensitivity on initial and subsequent testing and an unreliable FDT as 33% fixation losses or false positives. We performed FDT perimetry (C-20-5) at baseline and 3 years laterin 256 non-English speaking residents of Southern India. We excluded patients with unreliable results in either eye with baseline testing. We defined a repeatable result if the result was a screening failure or screening pass for both baseline and follow-up testing. We used kappa statistics, correlation analyses, and Bland-Altman plots to examine repeatability. We controlled for inter-eye dependence using generalized estimating equations.
We tested 512 eyes of 256 participants in 2000 and 2003, and include 458 participants (89.5%) with reliable baseline FDT results. Overall, 288/458 (62.9%) had repeatable results over the 3-year test period. Of those with repeatable results, 258/288 (90%) eyes remained as a screening pass and 30/288 (10%) remained as a screening failure. Of those with nonrepeatable results, 85/170 (50%) eyes with screening pass results converted to screening failure results, 24/170 (14%) of those with screening failure results converted to screening pass, and 51/170 (30%) had screening pass or screening failure results on baseline testing and indeterminate results on follow-up testing. Kappa statistic was 0.21. We found no significant association between repeatability and age, gender, cup to disc ratio, lens opacity classification score, or refractive error (p>0.05). .
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