Aim: To see if scotoma detected with frequency doubling technology (FDT) is confirmed by Humphrey field analyser (HFA) 3 years later. Methods: Subjects were first examined with the screening C- 20- 1 program of FDT. The visual field was examined annually for 4 years using HFA program C30- 2. The central 58 test points in HFA were assigned to one of the 17 clusters corresponding to FDT test points. Each cluster was represented as the lowest probability symbol of total deviation (TD) of the HFA test points included in the cluster. Clusters were graded normal, suspected scotoma, and scotoma depending on probability of TD- 5% or more, 5% - 1% , less than 1% , respectively. Relative risk (RR) of abnormality on FDT for future scotoma on HFA was estimated. Results: 80 eyes of 42 patients were followed up for 4 years. While 4.0% of normal clusters of HFA with normal FDT results developed into scotoma cluster, 20.8% of normal clusters with abnormal FDT results developed into scotoma cluster with HFA at the third year. RR for future scotoma was 5.24 (95% CI, 2.75 to 10.0, p<0.05). Conclusion: An abnormal result in FDT shows a high risk of future scotoma on HFA after 3 years even if the original HFA perimetry showed normal results.
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