A new strategy for threshold estimation, FASTPAC, has been introduced for the Humphrey Field Analyser with the aim of improving the efficiency of visual field examination without loss of accuracy. FASTPAC was compared to the standard 4-2 double staircase strategy in 98 normal volunteers (age 23-83 years). One eye of each subject was examined with both strategies on two visits using Program 30-2. The order of strategy was randomised. FASTPAC examination time was 43% faster than the standard algorithm, but the mean sensitivities were similar. Short-term fluctuation was 24% higher with FASTPAC (P < 0.001). Most parameters were adversely affected by increasing age. FASTPAC offers a valid alternative to the standard strategy in the examination of suspected normal fields and should always be considered as an alternative to the threshold-related screening strategies. The performance of the algorithm in the identification of field loss and in areas of reduced sensitivity awaits further study.

Improvements in B-Y perimetric performance occurred as the familiarity with the test increased, regardless of previous W-W experience. Failure to account for such improvement could reduce the efficiency of B-Y perimetry.

The study investigated the effects of induced forward light scatter on the normal blue-on-yellow perimetric profile. Light scatter was induced using 0.00%, 0.08% and 0.16% suspensions of 500-nm-diameter polystyrene microspheres contained in optical cells. White-on-white, yellow-on-yellow and blue-on-yellow perimetry was performed using a modified Humphrey Field Analyser 640. Fifteen subjects performed perimetry with each of the scatter suspensions placed before the eye and in the cell-free situation. The degree of induced scatter for each cell was quantified using the direct compensation technique of van den Berg at small, medium and large angles of scatter. Straylight increased and perimetric sensitivity decreased with increase in scatter concentration. Forward light scatter caused a general reduction in sensitivity for all stimuli, particularly for the blue-on-yellow stimulus. This finding may have implications for the interpretation of the glaucomatous visual field in the presence of forward light scatter.

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