|Title||ACCURACY IN JUDGING GAZE ECCENTRICITY: CAN CONFRONTATION VISUAL FIELD TESTING BE MORE QUANTITATIVE?|
|Author, Co-Author||Morvari Ahi, Catherine Johnson, Luisa Mayer, Li Deng|
|Abstract|| PURPOSE: To guide the development of a quantitative test of confrontation visual field for non-verbal patients, we investigated the accuracy of adult judgments of the visual angle of another adult’s gaze eccentricity.
METHODS: Two experienced adult "gazers" shifted their gaze to 9 predetermined, fixed eccentricities between 10° and 90° in 10° steps on 2 oblique half meridia (45° and 225°). Fixation and peripheral targets were identical 6° diffuse white lights presented on a black double-arc perimeter. Ten adult "observers" judged the eccentricity of the gazer’s gaze on 4 trials/eccentricity in each of 4 conditions (2 gazers and 2 meridia). The median of 4 trials was analyzed.
RESULTS: Median errors of observers ranged from -25° (underestimation) to +20° (overestimation), with a range of mean signed errors of -4° to +2.625° across the 9 eccentricities. A small statistically significant gazer difference (p<0.01) was driven by one subject (p>0.3 after exclusion). There was no significant difference between meridia, nor were there any significant interactions (all p>0.05). Overall, the judgment error was negatively correlated with eccentricity (slope= -0.086, p=0.001). The eccentricity difference was also significant (main effect p<0.001) when treated as a categorical variable. The mean error at 10° was significantly greater than zero (p<0.01) (overestimation). The mean errors from 60° to 90° were significantly less than zero (all p<0.04) (underestimation).
CONCLUSIONS: Accuracy of adult judgments of gaze eccentricity depends upon eccentricity in our experimental conditions. The nearest eccentricity was overestimated whereas far eccentricities were underestimated. Despite notable differences in ocular/orbital appearance of the two gazers, there were no systematic differences in judgment errors between gazers. Error judgments were quite variable. Future research is needed to evaluate the effects of feedback and practice on judgments of eccentricity.
|Affiliation of Co-Authors||New England College of Optometry, New England College of Optometry, New England College of Optometry|