Purpose: To test the ability of Frequency Doubling Technology (FDT) perimetry to reveal defects in the same field quadrants as detected by Standard Automated Perimetry (SAP).

Patients and methods: Ninety-two eyes with open-angle glaucoma and documented visual field defects by threshold SAP (Octopus Dynamic Program) also underwent threshold FDT testing after successfully passing the screening FDT test.

Results: All eyes revealed varying stages of SAP defects while only 80 revealed FDT damage: 31: 21 eyes in the early field loss stage, 36: 35 in the moderate category, and 25: 24 in the severe one in SAP vs FDT, respectively. SAP was able to detect abnormalities in 74% and 79% of the superotemporal, and inferotemporal quadrants, respectively, while the corresponding FDT figures were 70% and 69% for the same quadrants (p<0.05 each). As for the nasal hemifield, SAP detected defects in 73% and 81% of the superonasal and inferonasal quadrants, respectively, compared to 69% and 66% for FDT (p<0.001 each). The test duration per individual eye was significantly shorter with FDT than with SAP (p<0.05).

Conclusion: Beside the already established lower sensitivity of FDT compared to SAP, this study demonstrates a significantly poorer ability of FDT in detecting the same field quadrant defects, especially in the early stages of glaucomatous damage.