Abstract
Purpose: :
To assess age-corrected normative differential luminance sensitivity (DLS) values for automated static perimetry with a new, fast strategy (GATE = German Adaptive Threshold Estimation) for the entire (80 degree) visual field.
Methods: :
Eighty-one normal subjects, aged from 10 to 79 years were enrolled in this study, which was performed on the new Octopus 900 perimeter (HAAG-STREIT Inc., Koeniz, Switzerland). Eighty-six static stimuli (Goldmann size III = 26') up to a maximal eccentricity of 80 degrees, with a condensation towards the visual field centre, were presented on a homogeneous background under photopic conditions (luminance level 10 cd/m²). A fast thresholding 4-2 dB algorithm with at least one reversal was used. Local DLS values were estimated by applying the maximum likelihood (ML) procedure. A smooth mathematical model was fitted to the data set, allowing to predict the local DLS values for any location of the entire visual field.
Results: :
Model fit was satisfactory (R² = 0.72). The residual standard deviation over the entire 80 degree visual field amounted to 2.52 dB. The number of questions asked (mean) was 338 for the GATE strategy (compared to 410 for the conventional 4-2 dB bracketing algorithm) in this cohort of normal subjects. Examination duration (median, without breaks) was 13.5 min. (95% RI 10.7 - 20.4 min).
Conclusions: :
A smooth mathematical model allows for the prediction of local differential luminance thresholds of normal subjects for any location within the entire 80 degree visual field, obtained with the new Octopus 900 perimeter. In normal subjects, the new, fast GATE strategy reduces the number of questions asked by approximately 18%, compared to a full threshold bracketing algorithm. Subsequent examinations with GATE are related to previous exams and therefore further reduce the examination duration.
Clinical Trial: :
IRB Tuebingen,217/2006
Keywords: perimetry • visual fields • nerve fiber layer