97th DOG Annual Meeting 1999
INFLUENCE OF DIFFERENT STIMULUS VELOCITIES IN KINETIC PERIMETRY
B. Wabbels, G. Kolling
In manual perimetry, the stimulus velocity depends on the examiner. Goldmann recommends 1-2°/s, Flammer 3-5°/s, Johnson 4°/s. In clinical practice the velocity used is often higher. In the present study the influence of different stimulus velocities is tested with constant rates with autokinetic perimetry using different stimuli in the entire visual field.
Subjects and methods: Fifteen persons aged 20-30 years without ocular pathology were tested various times with an Oculus Twinfield Perimeter with stimulus velocities ranging from 1°/s to 7°/s along the meridians 0°, 30°, 60°,... up to 330°. Background luminance, stimulus size and -luminance were chosen according to the standard of Goldmann-perimetry. The subjects had manual Goldmann-perimetry as a control.
Results: With increasing test velocity the size of the field inside a specific isopter decreased. This effect was already present at velocity rates starting from 3°/s. For the stimulus I1 the means for the different meridians ranged from 17° to 44° for a velocity of 1°/s, from 15° to 39° for a velocity of 3°/s, from 13° to 36° for a velocity of 5°/s and from 6° to 32° for a velocity of 7°/s respectively. With increasing velocity, the variability of the results increased.
Conclusion: In manual Goldmann-perimetry many examiners use stimulus velocities of at least 3°/s. This study demonstrates that such a testing procedure could lead to poor accuracy and non reliable results even in young and healthy subjects. Autokinetic perimetry -as compared to manual perimetry- may therefore improve visual field standardization.
University Eye Hospital Heidelberg, INF 400, D-69120 Heidelberg