Kimberly R. Woodward

Repeatability of automated perimetry: a comparison between standard automated perimetry with stimulus size III and V, matrix, and motion perimetry.

PURPOSE Standard automated perimetry (SAP) shows a marked increase in variability in damaged areas of the visual field. This study was conducted to test the hypothesis that larger stimuli are associated with more uniform variability, by investigating the retest variability of four perimetry tests: standard automated perimetry size III (SAP III), with the SITA standard strategy; SAP size V (SAP V), with the full-threshold strategy; Matrix (FDT II), and Motion perimetry. METHODS One eye each of 120 patients with glaucoma was examined on the same day with these four perimetric tests and retested 1 to 8 weeks later. The decibel scales were adjusted to make the tests scales numerically similar. Retest variability was examined by establishing the distributions of retest threshold estimates, for each threshold level observed at the first test. The 5th and 95th percentiles of the retest distribution were used as point-wise limits of retest variability. Regression analyses were performed to quantify the relationship between visual field sensitivity and variability. RESULTS With SAP III, the retest variability increased substantially with reducing sensitivity. Corresponding increases with SAP V, Matrix, and Motion perimetry were considerably smaller or absent. With SAP III, sensitivity explained 22% of the retest variability (r(2)), whereas corresponding data for SAP V, Matrix, and Motion perimetry were 12%, 2%, and 2%, respectively. CONCLUSIONS Variability of Matrix and Motion perimetry does not increase as substantially as that of SAP III in damaged areas of the visual field. Increased sampling with the larger stimuli of these techniques is the likely explanation for this finding. These properties may make these stimuli excellent candidates for early detection of visual field progression.

Sensitivity and specificity of the Humphrey Matrix to detect homonymous hemianopias.

PURPOSE To compare the sensitivity and specificity of the Humphrey Matrix frequency-doubling perimeter (Carl Zeiss Meditec, Inc., Dublin, CA) to that of standard automated perimetry (SAP) in detecting homonymous hemianopic visual field defects. METHODS Thirty-three patients with homonymous hemianopias and 50 normal subjects were tested with SAP with the Humphrey Visual Field Analyzer (SITA standard program 24-2) and Humphrey Matrix frequency-doubling perimetry, program 24-2 (Matrix) on the same day. Patients with hemianopias had lesions of the retrochiasmal visual system that were documented by magnetic resonance imaging or by computed tomography. To be classified as a hemianopic visual field defect, the abnormal test location had to be homonymous, respect the vertical meridian, and have no additional scattered abnormal points that obscured the hemianopic pattern. The sensitivity and specificity of SAP and Matrix in detecting hemianopic defects were calculated. The chi(2) test was used to test for differences between groups. RESULTS The sensitivity for hemianopic defects by total deviation probability plots was 75% for SAP and 59% for Matrix (not statistically significant, P = 0.29). The sensitivity of hemianopic defects by pattern deviation probability plots was 88% for SAP and 69% for Matrix (not statistically significant, P = 0.13). The specificity of total deviation probability plots was 84% for SAP and 86% for Matrix. The specificity of the pattern deviation probability plots was 68% for SAP and 74% for Matrix. CONCLUSIONS Although there was no statistically significant difference between the Matrix and SAP in the detection of hemianopias, the sensitivity of SAP was higher, probably because of the obscuration of defects by scattered abnormal test locations with the Matrix.

Total Deviation Probability Plots for Stimulus Size V Perimetry: A Comparison With Size III Stimuli

OBJECTIVE To compare empirical probability plots in patients with glaucoma for size V and III perimetry testing. METHODS We computed empirical probability plot percentile limits after testing 60 age-matched controls tested with both size III (Swedish interactive thresholding algorithm) and size V (full threshold) perimetry twice. Probability plots of 120 patients with glaucoma tested in the same way were computed. We compared the number of abnormal test locations in the 2 stimulus sizes; we then compared these results with those from size III StatPac software (Zeiss Humphrey Systems, Dublin, California) using 2-way repeated-measures analysis of variance. RESULTS We found a similar number of abnormal test locations (P < or = .05) for the size III and size V testing conditions identified by the probability plots (no significant difference); there were significantly fewer abnormal locations using StatPac (size III) than from our size III database. When results were stratified by mean deviation, the mild visual loss group again did not show any significant differences between sizes III and V. CONCLUSIONS Size V full-threshold testing gives a similar number of abnormal test locations in patients with glaucoma compared with the size III Swedish interactive thresholding algorithm standard test. Size V testing, with its greater dynamic range and lower variability, may be a viable alternative to size III testing in patients with glaucoma.

Humphrey Matrix Perimetry in Optic Nerve and Chiasmal Disorders : Comparison with Humphrey SITA Standard 24-2

PURPOSE To compare the Humphrey Matrix 24-2 perimetry (Matrix; Carl Zeiss Meditec, Inc., Dublin, CA) with the standard automated perimetry Humphrey Visual Field Analyzer using SITA (Swedish Interactive Threshold Algorithm) program 24-2 (SAP; Carl Zeiss Meditec, Inc.) in neuro-ophthalmic disorders affecting the optic nerve and chiasm. METHODS Matrix and SAP were performed on 93 patients with neuro-ophthalmic disorders affecting the optic nerve and optic chiasm. Three readers compared the total and pattern deviation probability plots and judged the similarity and the extent of the visual field defects. The sensitivity and specificity of both perimeters were calculated. RESULTS Concordance was good in 61%, fair in 30%, and poor in 9% of the total deviation plots. For the pattern deviation, concordance was good in 52%, fair in 34%, and poor in 14%. The extent of field loss was equal in 50%, 23% more extensive with Matrix, and 27% more extensive with SAP for total deviation plots. For the pattern deviation, the extent was equal in 47%, 20% more extensive with Matrix and 33% more extensive with SAP. The sensitivity for detecting defects was 84% (SAP) and 77% (Matrix) for total deviation and 80% (SAP) and 79% (Matrix) for pattern deviation (no significant difference, P > 0.05). The specificity was 84% (SAP) and 86% (Matrix) for total deviation and 68% (SAP) and 74% (Matrix) for pattern deviation (no significant difference, P > 0.05). CONCLUSIONS The new Humphrey Matrix 24-2 testing strategy provides a visual field testing method for optic nerve and chiasmal disorders that has fair to good concordance with the Humphrey SITA Standard 24-2 program. Both tests have similar sensitivity and specificity.

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

PurposeTo compare the false-positive (FP) response rates between 2 methods used by the Humphrey Field Analyzer in glaucoma patients. MethodsOne 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, 2×2 analysis of variance was used to examine error rates, and FP rates for visits 1 and 2 were regressed to investigate its relationship. ResultsFor 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). ConclusionsThe RTW method seems to underestimate FP response rates.