Modified attentional fields in ageing

Purpose:  Clinical vision testing tends to underestimate age‐related visual decline. We have modified an automated perimeter by adding a second task at fixation and have investigated visual fields in conditions of focused (FA) and divided attention (DA). Methods:  Two lasers were mounted on a Humphrey Visual Field Analyzer (Carl Zeiss, Jena, Germany). They projected red targets 2 mm either side of the standard fixation target. Fifteen young (mean age: 20 ± 1.4 years; range: 18–23) and 15 healthy old subjects (72 ± 5.1 years; range: 65–80) were assessed under FA using Fastpac 30–2 program (sequence 1). Subjects then repeated the test twice under DA (sequences 2 and 3), in which they were instructed to press a second handheld button in response to an asynchronously presented central laser target. They also responded to continuing laser targets after the threshold program finished. Results:  For old subjects under DA, the mean threshold increased by 2.87 cd m −2 (sequence 2) and 0.8 cd m −2 (sequence 3) compared with FA (sequence 1). By comparison young subjects increased by 0.03 cd m −2 (sequence 2) and decreased by 0.55 cd m −2 (sequence 3). Compared with young subjects, mean threshold for old subjects was 8.44 cd m −2 (sequence 2) and 6.89 cd m −2 (sequence 3) greater. Mean reaction times for the fixation task alone were comparable (young: 353 ± 46 ms vs old: 352 ± 52 ms). However, when combined with the threshold field task, reaction times increased by much more in the old group (e.g. 497 ± 46 ms vs 557 ± 50 ms sequence 2). Conclusion:  The visual fields of old subjects were only slightly reduced in DA conditions although the reduction was clearly greater than for the young group. There were marked increases in the reaction times of the older group to targets presented at fixation. Continuing studies will assess impact of DA on patients with ocular and cerebral disease.