The results generated by the STATPAC program of the Humphrey Field Analyzer (Allergan Humphrey, San Leandro, Calif) from 72 eyes with documented early visual field loss and 98 normal eyes were examined. When global summary indexes and their significance levels were used to compare the tested eyes with age-matched normal values, STATPAC yielded a sensitivity of 93% and a specificity of 84%. In comparison, analysis by an independent, previously reported method yielded a sensitivity of 97% and a specificity of 90%. STATPAC results were strongly influenced by the reliability of the tested subjects.