Frequency doubling technology perimetry in age-related macular degeneration

The role of frequency doubling technology perimetry (FDT) in glaucoma has been promising in terms of speed and simplicity as well as in its high sensitivity and specificity compared to conventional automatic perimetry. In this study, we investigated the possible role of FDT in exudative type age-related macular degeneration (ARMD).

FDT using full-threshold C-20 mode was performed in patients with ARMD. The macula was classified into 3 zones by the distance from the fovea center (zone I: central 1 degrees, zone II: central 3 degrees except zone I, zone III: central 5 degrees except zones I & II). The lesion was scored into 3 ranks by the area ratio of involvement in each zone. The retinal scores, visual acuity and disease duration were compared with the FDT scores of the central target, which was graded into 5 ranks according to the probability level of abnormal points on total deviation plots using Spearsman's rank correlation method.

Measurements from 32 eyes (30 patients) with exudative ARMD were collected. The FDT scores of the central target correlated significantly with the lesion scores in zone III (p = 0.033), but not with the lesion scores in central 3 degrees (zone I: p = 0.383, zone II: p = 0.077). Visual acuity was weakly correlated with the FDT scores of the central target (p = 0.022), and the lesion scores in zone III (p = 0.038), but strongly correlated with the lesion scores in zone I and zone II (p < 0.001). The FDT scores of the central target were within normal limit in 20 eyes.

Our results suggest that FDT using full-threshold C-20 mode is not sensitive enough for the detection of small macular lesions in ARMD. Therefore, it might not be a useful functional evaluation in ARMD. Further modification of the central target of FDT is necessary to detect small macular lesions in ARMD.