[Effect of faulty refraction and artificial media opacities on visual acuity perimetry]

For resolution perimetry according to Frisén, 50 test locations in the central visual field are examined. Compared with conventional perimetry the test time is rather short: 5-10 min per eye. For routine application of this new perimetric technique it is important to know to what extent the threshold values are affected by refractive defocus or media opacities. To answer this, 20 eyes of 20 normal subjects were tested both with a refractive defocus (0, +1, +3, +6, +9 and +12 dpt sph) and with artificial media opacities, using occluders according to Bangerter to reduce visual acuity to average values of 0.61, 0.27, 0.14 and 0.07. The results of the present study show that even a slight refractive defocus or a slight artificial media opacity induces a marked increase in threshold values. Mean Ring score MR and defocus are quadratically correlated (MR2/defocus: r = 0.9973, p less than 0.001), and MR is linearly correlated with the Reduced Luminance Factor 1(15) (MR/1(15): r = 0.9978, p less than 0.001). Clinical evaluation of the test results of the ring perimeter thus has to take into account the influence of refractive defocus and media opacities.