Purpose:
To compare the false positive rates between two different methods for estimating false positive catch trials used by the Humphrey Field Analyzer (HFA) in glaucoma patients.
Methods:
One eye of 120 Glaucoma patients was tested twice within 2 months with Size III 24-2 SITA Standard and Size V 24-2 Full Threshold perimetric test procedures. False positive (FP) rates were obtained with the response time window method (RTW) used by SITA and the blank presentation (BP) method of the size V full threshold procedure. False negative (FN) catch trial rates were also examined. Wilcoxon tests were used to examine error rates, and FP rates for visit 1 and 2 were regressed to investigate their relationship.
Results:
Glaucoma patients had higher mean FP rates with RTW than BP on visit 1 (p=0.006, 2.3% vs. 1.68%) and higher mean FN rates as well (p=0.001; 4.1% vs. 1.7%; Table). When comparing visit 2, glaucoma patients had significantly higher FN’s rates with RTW than BP (p=0.001; 3.61% vs. 1.22%). Linear regression indicated that, for visit 1 in glaucoma patients, FP rates in RTW accounted for only 6.63% of the variability in BP error rates; and only 3.88% in visit 2.
Conclusions:
The response time window method is not a good predictor of false positive rates obtained using the blank presentation procedure.
Keywords: perimetry • visual fields