A comparison of three methods for abbreviating G1 examinations

The G1 glaucoma program is now widely employed in Octopus automated perimetry in order to detect early visual field damage and as an aid in regular follow up. For some patients, however, the examination duration, about 20 minutes, can be excessive. Three methods which could be used for an abbreviated initial screening phase were studied: 1) examining 30 test locations with full 2 dB minimum step size bracketing; 2) using all 59 test locations, but with 4 dB minimum step size bracketing; and 3) using 30 test locations and 4 dB minimum step size. Two indices derived from these abbreviated examination procedures were compared to those obtained from the first phase of the G1 program. The study was based on data of 1008 visual fields of both normal and pathological eyes. It was found that the 30 test location full bracketing method yielded the best agreement with the results obtained with the first phase of the G1 program. Recommendations concerning the optimal utilization of these methods in possible future versions of the G1 program are included.