The influence of induced forward light scatter on the normal blue-on-yellow perimetric profile

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.