The Repeatability of Mean Defect with Size III and Size V Standard Automated Perimetry

Abstract

PURPOSE. The mean defect (MD) of the visual field is a global statistical index used to monitor overall visual field change over time. Our goal was to investigate the relationship of MD and its variability for two clinically used strategies (Swedish Interactive Threshold Algorithm [SITA] standard size III and full threshold size V) in glaucoma patients and controls.METHODS. We tested one eye, at random, for 46 glaucoma patients and 28 ocularly healthy subjects with Humphrey program 24-2 SITA standard for size III and full threshold for size V each five times over a 5-week period. The standard deviation of MD was regressed against the MD for the five repeated tests, and quantile regression was used to show the relationship of variability and MD. A Wilcoxon test was used to compare the standard deviations of the two testing methods following quantile regression.RESULTS. Both types of regression analysis showed increasing variability with increasing visual field damage. Quantile regression showed modestly smaller MD confidence limits. There was a 15% decrease in SD with size V in glaucoma patients (P ¼ 0.10) and a 12% decrease in ocularly healthy subjects (P ¼ 0.08).CONCLUSIONS. The repeatability of size V MD appears to be slightly better than size III SITA testing. When using MD to determine visual field progression, a change of 1.5 to 4 decibels (dB) is needed to be outside the normal 95% confidence limits, depending on the size of the stimulus and the amount of visual field damage. (Invest Ophthalmol Vis Sci.

Choice of Stimulus Range and Size Can Reduce Test-Retest Variability in Glaucomatous Visual Field Defects

“…44 Figure 8 shows test-retest variability for both MD and sector averages for the subjects in experiment 3. This shows the same trend as in a prior study, 48 with variability slightly lower for larger stimuli. For MD, the limits of agreement spanned 0.55 log units for size III stimuli, 0.38 log units for frequency-doubling stimuli, and 0.29 log units for the Gabor stimuli.…”

“…Test-retest variability is much lower for MD than for individual locations, 48 as well as for perimetric sensitivities averaged in terms of optic nerve sectors that serve those retinal locations. 44 Figure 8 shows test-retest variability for both MD and sector averages for the subjects in experiment 3.…”

Significant Glaucomatous Visual Field Progression in the First Two Years: What Does It Mean?

“…The criterion for significance was P < 0.05. Although MD variability increases as damage in the visual field increases, 12,13 this was not modelled as changes are typically small for the rates of change and length of visual field series investigated here (a change in standard deviation of ∼0.04 dB for every decibel of decrease in MD). 13 Visual field series from 100,000 patients were simulated for each condition tested.…”

The correlation between retinal sensitivity assessed by microperimetry and contrast sensitivity in diabetic macular oedema

“…MP was performed with Goldmann III size dot stimuli and a four to two staircase strategy. The size of the Goldmann III dot stimuli was 4 mm 2 and it was about 0.43° 17. RS was measured at 13 stimulus points (one point at the fixation centre (RS-c), four points marked by the cross shape for the central two degree areas and eight points marked by a ring shape between the central two-degree area and the four-degree area) (figure 2).…”