The reliability of Frequency-Doubling perimetry in young children

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.