Angioscotoma detection with fundus-oriented perimetry - A study with dark and bright stimuli of different sizes

Fundus-oriented perimetry (FOP) was used to evaluate the effectiveness of d ifferent-sized bright and dark stimuli in detecting and quantitatively meas uring angioscotoma. The foveolas and optic disks of digitized fundus images were aligned with their psychophysical counterparts to construct individua l grids of perimetric stimuli. Each grid included a linear set of test poin t locations crossing a retinal vessel. Angioscotomas immediately became vis ible in nine of 13 healthy normal volunteers rested with FOP. Additional ma thematical processing of local loss of differential light sensitivity (dls) disclosed an angioscotoma for at least one stimulus condition in all perso ns tested. The angioscomas were usually deeper for small (12') targets than for large (32') ones. On the other hand, the overall noise at dls threshol ds was generally higher for small than for large stimuli regardless of whet her the stimuli were bright or dark. No noteworthy differences were found i n detection rates or signal-to-noise ratios under different stimulus condit ions (dark/bright/small/large). FOP permits the individual arrangement of s timuli for specific morphological conditions and is thus capable of detecti ng even minute visual field defects such as angioscotomas. (C) 1999 Elsevie r Science Ltd. All rights reserved.