Attentional visual field analysis using Fastpac

Abstract

Aim: To investigate the effect of dividing attention using conventional automated perimetry in normal, healthy young and elderly subjects. Method: A Humphrey Visual Field Analyzer was modified by the addition of external lasers, which introduced a task additional to the standard threshold field test by presenting red targets at fixation. Young and elderly subjects inexperienced in perimetry were recruited. Two standard 30-2 Fastpac visual fields were examined. Three attentional visual fields were completed which varied in difficulty. The number of targets at fixation decreased from 72 (high) to 48 (medium) and then 24 (low) in each attentional visual field. The effects on visual sensitivity were compared by dividing the central 30° into four regions dependent on eccentricity. Accuracy, durations and manual response times in the different conditions were also compared. Results: In high-distraction conditions elderly subjects showed reduced visual sensitivity whereas young subjects had similar sensitivity compared with the sensitivity for standard visual fields. As the numbers of distractors was reduced visual sensitivity was shown to improve for both groups. The duration time to complete the attentional visual field increased for both groups compared with the standard fields but measures of accuracy were broadly similar in both standard and attentional visual field tests for both groups. The manual response times increased for both groups in attentional conditions. Conclusion: The loss in sensitivity in high-distraction attentional visual fields for elderly subjects, longer durations and increase in response time suggest that motivational or cognitive status may have an impact on the interpretation of visual field results.