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PURPOSE.To determine the influence of several factors on standard automated perimetry test results in glaucoma.METHODS. Longitudinal Humphrey field analyzer 30-2 Swedish interactive threshold algorithm data from 160 eyes of 160 glaucoma patients were used. The influence of technician experience, time of day, and season on the mean deviation (MD) was determined by performing linear regression analysis of MD against time on a series of visual fields and subsequently performing a multiple linear regression analysis with the MD residuals as dependent variable and the factors mentioned above as independent variables. Analyses were performed with and without adjustment for the test reliability (fixation losses and false-positive and false-negative answers) and with and without stratification according to disease stage (baseline MD).RESULTS. Mean follow-up was 9.4 years, with on average 10.8 tests per patient. Technician experience, time of day, and season were associated with the MD. Approximately 0.2 dB lower MD values were found for inexperienced technicians (P < 0.001), tests performed after lunch (P < 0.001), and tests performed in the summer or autumn (P < 0.001). The effects of time of day and season appeared to depend on disease stage. Independent of these effects, the percentage of false-positive answers strongly influenced the MD with a 1 dB increase in MD per 10% increase in false-positive answers. The variability of SAP test results depends on many factors. A well-known factor is disease stage. 1,2 Other factors are patient motivation and technician performance, the latter via appropriateness of refraction and patient instruction, reassurance before the test, and patient monitoring during the test. [3][4][5] Circadian rhythms and seasonal influences may also contribute to the variability. These periodicities may influence SAP test results in at least two different ways. First, patients need a good cognitive function to perform perimetry. In an extensive review, Blatter et al. 6 described a daily variation in cognitive function in humans. Cognitive function deteriorated over the day in the elderly (at the typical age of a glaucoma patient), whereas the opposite is the case in young subjects. Second, SAP measures a threshold sensitivity of the visual system. Earlier studies in humans showed a daily variation in retinal visual sensitivity, suggesting lower sensitivities in the early morning. CONCLUSIONS.7-9 Besides a daily variation, a seasonal (circannual) variation might also be present. After all, exposure to light varies per season and prior light history affects light sensitivity.10 Indeed, retinal sensitivity seems to be highest in the spring. 11,12 Variability is entangled with reliability, which is commonly assessed by reliability indices and displayed as the percentages of fixation losses (FL) and false-positive (FP) and false-negative (FN) answers. Two issues concerning reliability are relevant to this study. First, whether reliability as assessed by the reliability indices influences variability. Se...

BackgroundVisual field testing is an essential part of glaucoma care. It is hampered by variability related to the disease itself, response errors and fatigue. In glaucoma, blind parts of the visual field contribute to the diagnosis but - once established – not to progression detection; they only increase testing time. The aims of this study were to describe the persistence and spatial distribution of blind test locations in standard automated perimetry in glaucoma and to explore how the omission of presumed blind test locations would affect progression detection.Methodology/Principal FindingsData from 221 eyes of 221 patients from a cohort study with the Humphrey Field Analyzer with 30–2 grid were used. Patients were stratified according to baseline mean deviation (MD) in six strata of 5 dB width each. For one, two, three and four consecutive <0 dB sensitivities in the same test location in a series of baseline tests, the median probabilities to observe <0 dB again in the concerning test location in a follow-up test were 76, 86, 88 and 90%, respectively. For <10 dB, the probabilities were 88, 95, 97 and 98%, respectively. Median (interquartile range) percentages of test locations with three consecutive <0 dB sensitivities were 0(0–0), 0(0–2), 4(0–9), 17(8–27), 27(20–40) and 60(50–70)% for the six MD strata. Similar percentages were found for a subset of test locations within 10 degree eccentricity (P>0.1 for all strata). Omitting test locations with three consecutive <0 dB sensitivities at baseline did not affect the performance of the MD-based Nonparametric Progression Analysis progression detection algorithm.Conclusions/SignificanceTest locations that have been shown to be reproducibly blind tend to display a reasonable blindness persistence and do no longer contribute to progression detection. There is no clinically useful universal MD cut-off value beyond which testing can be limited to 10 degree eccentricity.