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Efficacy of Frequency Doubling Technology Perimetry in Non-arteritic Anterior Ischaemic Optic Neuropathy with Altitudinal Visual Field Defects

The aim of the study was to evaluate the ability of frequency doubling technology perimetry to detect altitudinal hemifield defects in cases of non-arteritic anterior ischaemic optic neuropathy. Thirty eyes of 24 cases of the disorder with typical altitudinal visual field defects underwent standard automated (Humphrey 24-2) and frequency doubling technology (N-30 threshold) perimetry. For both techniques locations showing a defect of p < 5% were considered abnormal and the mean percentage defect of both the involved and uninvolved hemifields and global visual field parameters were compared. The mean percentage defects for the involved and uninvolved hemifields were comparable (p = 0.1 and p = 0.07, respectively) but there were statistically significant differences in fixation losses and in test duration (p < 0.001 and p < 0.001, respectively) for the two techniques. The authors conclude that frequency doubling technology perimetry is reliable and easily performed in patients with altitudinal visual field defects. The similarity of the extent of visual field defects found using the two techniques suggests that frequency doubling technology perimetry can be used for the rapid detection of altitudinal defects in anterior ischaemic optic neuropathy.