Scotoma mapping by semi‐automated kinetic perimetry: the effects of stimulus properties and the speed of subjects' responses

Abstract

ABSTRACT.Purpose: The study aimed firstly to determine the effects of stimulus variables on the detection of a scotoma border and, secondly, to study the reproducibility of the method during semi-automated kinetic perimetry. Methods: The size of the physiological blind spot in 18 young normal subjects was measured with a video-campimetric device, the Tu¨bingen computer campimeter (TCC). Kinetic stimuli of two different sizes and at four different levels of luminance were presented. Examinations were repeated within 2 weeks. Measurements were corrected for individual response times and the area of the blind spot was computed. The effects of stimulus strength and size and the repeatability of blind spot measurements were evaluated by an analysis of variance. Results: The physiological blind spot showed significant inter-and intraindividual variations in size (least square means ranging from 17 to 49 square degrees), with a standard deviation of 6.8 square degrees. The measured size of the blind spot increased as a function of decreasing stimulus value, by reducing either the relative brightness or the size of stimuli. Use of a correction for each subject's speed of responses nearly halved the level of random variance. The temporal sequence of measurements (the order in which they were performed) had no apparent effect on the calculated values of blind spot size. Conclusions: Semi-automated kinetic perimetry can determine the size of the physiological blind spot with good repeatability in young, normal subjects. Determination of each individual's speed of response and inclusion of this variable in the calculations reduced variance of the measure significantly. This study confirmed the presence of considerable interindividual differences in the size of the physiological blind spot.

The use of semi-automated kinetic perimetry (SKP) to monitor advanced glaucomatous visual field loss

“…In this small patient group (13 patients), the test-retest reliability of the Goldmann perimeter was 0.79 (also defined as a ratio). In the meantime, interactive software for an individual training and certification procedure for SKP has been introduced [18] Repeatability of SKP is reported in one recent study from Dolderer et al [3], dealing with the assessment of the blind spot. According to their report, SKP is highly repeatable with negligible mean difference in the blind spot area between examinations and a suitable instrument for detecting even small scotomas.…”

“…Furthermore, kinetic perimetry often gives useful results in elder or disabled patients, who are unable to cope with automated static procedures. Assessment of individual reaction time enables a correction for systematic shift of scotoma borders in order to approximate the scotoma size and location [3].…”

Peripheral Visual Fields in Children and Young Adults Using Semi-automated Kinetic Perimetry: Feasibility of Testing, Normative Data, and Repeatability

“…Dolderer et al 17 also reported large variation in scotoma size with a similar stimulus, the II2e. The authors have not found any previously reported data on whether the blind spot area increases during childhood.…”

“…The ability to accurately plot the blind spot scotoma is often clinically recorded as a measure of reliability. Dolderer et al 17 reported the minimum size in adults to be 17 deg 2 . The expected age at which a blind spot can be measured accurately has not previously been reported.…”

Detecting Functional Changes in the Patient’s Vision: Visual Field Analysis

“…Kinetic perimetry is usually conducted manually, although an automated perimetry program is now available on the Octopus perimeter. 27 Static and suprathreshold static perimetry can be performed in a manual or automated fashion. For each of these forms of perimetry, testing is normally performed on one eye that has a proper refractive correction for the testing distance, with the other eye occluded.…”