Using frequency-doubling perimetry to detect optic neuropathy in patients with Graves' orbitopathy

to test the ability of frequency-doubling technology (FDT) perimetry to detect dysthyroid optic neuropathy (DON).

Fifteen eyes of 15 patients with DON and 15 healthy control eyes were studied. Eligible eyes had a diagnosis of DON based on visual field abnormalities on standard automated perimetry and had visual acuity better than 20/30. FDT testing was performed using both the C-20-5 screening test and the C-20 full-threshold test. Normal and DON eyes were compared with regard to FDT mean sensitivity.

Sensitivity ranges were 40.0%-86.7% for the screening test, and 53.3%-100.0% (total deviation) and 20.0-93.3 (pattern deviation) for the C-20 threshold test. The corresponding specificity ranges were 86.7-100.0, 33.3-93.3, and 26.7-100.0, respectively. The best sensitivity/specificity ratios were for one abnormal point depressed <5% in the screening test (86.7%/86.7%), one point depressed <1% in the total deviation analysis (80.0%/86.7%), and one point depressed <2% in the pattern deviation analysis (80.0%/86.7%). DON eyes presented significantly lower than normal average sensitivity in the central, pericentral, and peripheral areas.

FDT perimetry is a useful screening tool for DON in eyes with normal or only slightly reduced visual acuity.