Normal Values of Short-Wavelength Automated Perimetry

Abstract

Background: The purpose of this study was to evaluate short-wavelength automated perimetry (SWAP, i.e., blue-yellow) in normal volunteers and to review the current normal values provided by the manufacturer. Methods: 28 eyes of 28 normal subjects (age range 21–48 years, mean age 36.5 years) had SWAP (Octopus 101, two phases of program G2, Interzeag AG, Schlieren, Switzerland). All subjects had normal eye examinations, refractive errors with spherical equivalents <5 diopters and astigmatism <2 diopters, normal intraocular pressures, no history of diseases affecting the visual field or nerve fiber layer, and normal white-white automated perimetry (Octopus 101, program G2). Results: 21% of the subjects (6/28) had to be excluded since visual field testing was not reliable (reliability factor >5%). With the normal values provided by the manufacturer, only 45% of the remaining subjects (10/22) had all other indices within normal limits. With the appropriate normal values based on the multicenter SWAP Octopus 101 study, 11% (3/28) were beyond the normal range: all had abnormal high sensitivities – 2 due to false-positive response. The normal value range for the index Mean Defect is remarkably wide (5.-, median, 95.- percentile: –4.4, –0.5, +5.3 dB, respectively). The normal value range for the index Loss Variance is surprisingly low and similar to standard perimetry (5.-, median, 95.- percentile: –1.7, 6.8, +21.2 dB², respectively). Conclusion: SWAP with the Octopus G2 program reaches appropriate specificity but only if the correct normal values of the multicenter SWAP Octopus 101 study are used. The variability between subjects is remarkably large. The variability within a visual field is similar for SWAP and standard perimetry as reflected by similar values for the visual field index Loss Variance. Further studies have to establish the sensitivity to detect a disease for SWAP on the Octopus 101.

Menstrual Cycle-Dependent Changes in Visual Field Analysis of Healthy Women

“…However, mean perimetric test durations obtained with both SAP and SWAP tests were not different throughout the menstrual cycle. Mojon and Zulauf [17], in their study on 28 normal subjects aged 21–48 years, showed that the variability within a visual field is similar for SWAP and standard perimetry. Bibawi et al [18]demonstrated that behavioral aspect of the visual field is most evident in the midluteal phase when the left hemisphere is more activated relative to the menstrual cycle.…”

Normal values for Octopus tendency oriented perimetry in children 7 through 13 years old

“…If only the MS is considered, it is theoretically possible that the truncated upper threshold combined with the effect of a high false positive rate (which obscures subnormal values from local defects) may collapse the MS into a predetermined region around the normal values for a 20-year-old. However, a recent normal value study [11] has shown that approximately 98% of the normal population are within this limit, reducing the skew to a minimum. It is nonetheless essential to also consider the clinical circumstances, the pattern deviation, the number of false positive catch trial responses, and the reliability indices when interpreting the visual field of an individual patient.…”

Recent developments in perimetry: test stimuli and procedures

“…37,38 SWAP on the Octopus 101 perimeter demonstrates remarkably large variability between normal subjects. 39 SWAP is more affected by ocular media absorption than SAP, 38 which can be problematic when assessing elderly patients. Thus, SWAP is not a preferred test for individuals with significant media opacity.…”