The reliability of Frequency-Doubling perimetry in young children

Abstract

Objective To evaluate whether healthy young children are able to perform automated static perimetry reliably using the frequency-doubling technology (FDT) perimeter. Design Prospective, observational case series. Participants Forty healthy children aged 4 to 14 years. Testing Subjects underwent, in 1 randomly chosen eye, 2 consecutive visual field (VF) tests using the C-20 full-threshold program of the commercially available FDT. Main outcome measures Global measures included mean deviation (MD), pattern standard deviation (PSD), test duration and reliability indices, including fixation losses and false-positive and false-negative errors. Fixation losses are checked 6 times throughout the examination, rather than being continuously monitored. Two scoring systems, based on the total deviation probability plot, classified each VF as normal or abnormal. Results All subjects completed the VF test. The better of 2 examinations (as determined by the MD score) was used for analysis. The average test duration was 4.9±0.7 minutes for the entire group. The mean MD and PSD were −0.78±4.9 and 6.7±6.2, respectively. A clear correlation to age was found for MD, PSD, abnormality of the VF, and test duration (all P<0.05). Of all VFs, 32.5% were unreliable, such that at younger than 8 years of age, 42.9% of the VFs were unreliable, compared with 23.1% for those older than 8 years. Younger than 8 years of age, 78.6% of VFs were abnormal, whereas for ages 8 years and older, 26.9% of VFs were abnormal. Conclusions Frequency-doubling technology seems to be a clinically feasible VF method for evaluating young children older than approximately 8 years of age. The reliability indices, MD, test duration, and the reproducibility of the VF test were found to be highly correlated with age, in such a way that these parameters all improved with increasing age.