[Threshold-oriented suprathreshold perimetry and threshold value perimetry with the Tübigen CC Automated Perimeter. A comparative study].

BACKGROUND

We compared the standard suprathreshold strategy to the so-called threshold splitting strategy with 5 and 2 dB steps. The aim of the study was to establish whether the threshold splitting strategy had advantages over the suprathreshold strategy that has been used to date.

METHOD

We examined the 30 degrees visual field in 49 volunteers using suprathreshold perimetry and on the same day threshold splitting perimetry on the Tübinger Automatic Perimeter CC. A total of 191 test points were examined in suprathreshold strategy. Using the threshold splitting strategy, 67 test points were examined, with a test-point design similar to other perimeters with the threshold splitting strategy. The criteria for inclusion in the study were central light sensitivity differences greater than 25 dB, fixation better than 80% and an illumination class density < 2.

RESULTS/DISCUSSION: The average duration of the examination using the suprathreshold strategy was 2-3 min quicker than the threshold splitting strategy in normal visual fields or small scotomas, but it took up to 15 min longer if large scotomas were presents. Interpretation of the scotoma configuration showed subjective differences: the smaller the scotoma, the greater the differences because of the fact that threshold splitting perimetry utilizes test points that are farther apart than those used in suprathreshold perimetry.