Abstract
PurposePerimetry is a both demanding and strenuous examination method that is often accompanied by signs of fatigue, leading to false responses and thus incorrect results. Therefore, it is essential to monitor the response quality. The purpose of this study was to evaluate the response time (RT) and its variability (RTV) as quality indicators during static automated perimetry.MethodsSize III Goldmann stimuli (25.7′) were shown with the OCTOPUS 900 perimeter in four visual field locations with 13 different stimulus luminance levels (0.04–160 cd/m2). An increased rate of false-positive and false-negative catch trials (25% each) served to monitor the response quality simultaneously together with response time recording. Data evaluation was divided into global and individual analysis. For global analysis, the agreement indices (AI, agreement between time periods with an increased number of false responses to catch trials and time periods with pathological response to time-based values set into relation to time periods in which only one of the two criteria was considered pathological) and for individual analysis, the Spearman correlation coefficients were calculated. Ophthalmologically normal subjects with a visual acuity ≥ 0.8, and a maximum spherical/cylindrical ametropia of ± 8.00/2.50 dpt were included.ResultsForty-eight subjects (18 males, 30 females, age 22–78 years) were examined. The total number of false responses to catch trials was (median/maximum): 6/82. RT and RTV were compared to the occurrence of incorrect responses to catch trials. The resulting individual Spearman correlation coefficients (median/maximum) were for RT: ρRT = 0.05/0.35 and for RTV: ρRTV = 0.27/0.61. The global analysis of the RTV showed agreement indices (median/maximum) of AIRTV = 0.14/0.47.ConclusionsAccording to this study, an increased portion of catch trials is suitable as a verification tool for possible response quality indicators. The RTV is a promising parameter for indicating the response quality.
Highlights
Perimetry is a strenuous examination method that often leads to an increasing lack of concentration and accompanying fatigue in patients, resulting in false responses and potentially incorrect perimetric results
The aim of this study is on the one hand to present a method with the help of which fatigue can be generated in a standardized, dosed form and its effect can be recorded and on the other hand to evaluate the response time (RT) and response time variability (RTV) as indicators of response quality during static automated perimetry
False responses to catch trials were considered as the gold standard for the quality of responses in this study
Summary
Perimetry is a strenuous examination method that often leads to an increasing lack of concentration and accompanying fatigue in patients, resulting in false responses and potentially incorrect perimetric results. Continuous quality assessment during perimetry was first introduced by Heijl and Krakau via fixation monitoring [2, 3]. The quality of visual field examinations is nowadays usually recorded by the stability of a central fixation in combination with the number of false responses to so-called catch trials [4,5,6]. Under clinical conditions usually a rate of only 3–5% of all stimuli is implemented as catch trials. A distinction is made between false-negative catch trials (those with highly supra-threshold, i.e. very high luminance levels which the patient would have to perceive at the corresponding normal visual field location) and falsepositive catch trials (exclusive auditory stimuli without any visual stimulus presentation at that time)
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