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J Glaucoma. 2008 Dec;17(8):626-30. doi: 10.1097/IJG.0b013e318168f03e.

A comparison of catch trial methods used in standard automated perimetry in glaucoma patients.

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Department of Neurology, University of Iowa, College of Medicine, and Veterans Administration Hospital, Iowa City, IA, USA.



To compare the false-positive (FP) response rates between 2 methods used by the Humphrey Field Analyzer in glaucoma patients.


One eye of one hundred and twenty glaucoma patients was tested twice within 2 months with 24-2 SITA Standard and 24-2 full threshold (FT) perimetric test procedures. FP rates were obtained with the response time window (RTW) method used by SITA and the blank presentation (BP) method of the size V FT procedure. False-negative (FN) catch trial rates were also examined. A repeated measure, 2 x 2 analysis of variance was used to examine error rates, and FP rates for visits 1 and 2 were regressed to investigate its relationship.


For FP rates on the first 2 visits, glaucoma patients had no significant differences comparing RTW (SITA) with BP (FT) (1.99% vs. 1.88%) and higher mean FN rates (4.11% vs. 1.69%, P=0.001); the FP rates at visit 2 were similar (1.69% vs. 2.08%) and FN rates were lower for both methods at visit 2. However, when comparing patients with FP responses that occurred with both RTW and BP methods, RTW rates were lower (3.58% vs. 7.72%, P=0.007).


The RTW method seems to underestimate FP response rates.

[Indexed for MEDLINE]

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