ANGIOSCOTOMATA ACID MORPHOLOGICAL FEATURES OF RELATED VESSELS IN AUTOMATED PERIMETRY

Aims-To determine principles which regulate the occurrence of angiosco tomata in automated static perimetry, variations in light sensitivity were correlated with the location and diameter of neighbouring retinal vessels. Methods-Ten normal eyes were tested with the Octopus 2000R, using a 0.431 degrees light stimulus. Sensitivity was quantified in po ints located around the blind spot, according to a regular, 0.5 degree s constant, grid pattern. From 336 to 443 locations were tested in eac h eye. The resulting printouts were superimposed on corresponding fund us photographs. At each tested point, the following five additional va riables were evaluated: the diameters of the closest and the second cl osest vessel (in 0.1 degrees units); the distances of the apparent loc ation of the tested point to the closest and the second closest vessel (in 0.25 degrees units); and the distance between the two closest ves sels (in 0.25 degrees units). Altogether, 3869 locations were tested a nd 23 214 values were quantified. Results-The following two conditions were found to be related to a reduction in sensitivity: (1) proximity (<0.25 degrees) to a large vessel (greater than or equal to 0.5 degre es in diameter); (2) proximity (<0.25 degrees to one of two adjacent ( <0.5 degrees distant), moderately large vessels (0.3 degrees to 0.4 de grees in diameter). in condition 1, sensitivity was 51.3% and specific ity was 92.2%; in condition 2, sensitivity was 16.2% and specificity w as 98.3%; and with a combination of conditions 1 and 2, sensitivity wa s 67.6% and specificity was 90.5%. Increase by 0.1 degrees of an adjac ent vessel which was 0.4 degrees in diameter markedly affected light s ensitivity. Conclusion-Modifications in vessel diameter are observed i n a number of circumstances, including adaptive vascular response to c hanges in ambient conditions and obstructive disorders of retinal vess els. These findings indicate that changes in vessel diameter time can result in fluctuation of sensitivity. It is concluded that, in contras t with what is commonly stated, when ocular media