Abstract
Purpose: :
To compare the reproducibility of second-generation frequency-doubling technology perimetry (FDT2, Humphrey Matrix) and standard automated perimetry (SAP) in glaucoma.
Methods: :
49 subjects with a range of severity of disease and 3 subjects with normal eyes were tested with SAP on the Humphrey Visual Field Analyzer with the Swedish Interactive Thresholding Algorithm (SITA) and with FDT2 on five occasions within a period of 8 weeks by a single operator. The repeatability of MD and PSD global indices was evaluated using standard deviations (SDs) and intra-class correlation coefficients (ICCs). Test-retest intervals were calculated for each threshold sensitivity levels for various combinations of one or multiple baseline and follow-up visual field tests.
Results: :
The global indices MD and PSD were highly repeatable for both SAP and FDT2 (ICCs > 0.95). The 90% prediction limit ranges of the raw thresholds, as might be used to decide whether progression had occurred, was relatively consistent over the range of severity for FDT2, while the threshold reproducibility was more dependent on disease severity with SAP. Combinations of either 1 or 2 baseline tests and of 1, 2 or 3 follow-up tests did not have major effects on the 90% retest range in the present study. However, the proportion of extreme values in the distribution of follow-up evaluations generally dropped when multiple tests were averaged.
Conclusions: :
The excellent test-retest characteristics of FDT2 may provide particularly valuable information while monitoring glaucoma. However, more knowledge about the comparative useful dynamic range of FDT2 and SAP instruments is needed to understand the clinical importance of these findings for the identification of glaucomatous progression, because the maximal severity of the disease that can be quantified may be different for the two methods.
Keywords: perimetry • clinical (human) or epidemiologic studies: systems/equipment/techniques