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Kristine K. Yin, Joshua R. Ehrlich, Nathan M. Radcliffe; Glaucomatous Progression Detected With Flicker Chronoscopy Is Associated With Spectral Domain Optical Coherence Tomography Abnormalities. Invest. Ophthalmol. Vis. Sci. 2011;52(14):4165.
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© ARVO (1962-2015); The Authors (2016-present)
Automated flicker chronoscopy is a promising technique for detecting glaucoma progression1,2, but concerns have been raised that the technique may produce false positives. We sought to assess the specificity of progression detected with flicker by evaluating retinal nerve fiber layer (RNFL) abnormalities with spectral domain optical coherence tomography (SD-OCT) in areas of progression identified with flicker.
Consecutive glaucoma or glaucoma suspect patients with serial optic disc photographs more than 6 months apart, who were imaged with SD-OCT (Cirrus, Carl Zeiss Meditec) in the follow up interval, were included for analysis. Eyes with poor quality or off-center photographs, or OCT signal strength less than 6 were excluded. If both eyes were eligible for inclusion, one eye was randomly selected. Serial photographs were loaded into PerfectView (Ophthalmology Imaging Systems, Sacramento, CA) or MatchedFlicker (Eye IC, Narbeth, PA) and evaluated by a reviewer masked to the findings of SD-OCT. Areas suspicious for progression were categorized as: rim loss, disc hemorrhage, or RNFL defect enlargement. SD-OCT RNFL thickness maps were then reviewed by a second masked reviewer to identify regions of RNFL outside normal limits (either by qualitative RNFL map or deviation map analysis). Agreement between the presence of progression on flicker and RNFL abnormalities on SD-OCT was assessed using the kappa statistic. Age, mean deviation (MD) on 24-2 SITA-standard automatic perimetry (HFA II, Carl Zeiss Meditec), and global RNFL thickness were considered as predictors of agreement.
386 patients with SD-OCT of the optic disc were screened for the presence of serial photographs. 49 eyes (49 patients) met inclusion criteria and were included in analysis. Flicker chronoscopy detected progression in 19 of 49 eyes (38.8%), while 33 of 49 eyes (67.3%) demonstrated abnormal SD-OCT. Progression detected with flicker was 93.8% specific for RNFL abnormalities on SD-OCT (kappa = 0.39, Z=3.25, p<0.001). Higher global RNFL thickness was a significant predictor of agreement between flicker chronoscopy and RNFL abnormalities on SD-OCT (85.0 ± 13.6 um vs 73.1 ± 15.6 um, p=0.01).
Glaucomatous progression detected with flicker chronoscopy demonstrates high specificity and moderate agreement when compared with RNFL abnormalities on SD-OCT, particularly in early glaucoma.1. VanderBeek BL, et al. Graefes Arch Clin Exp Ophthalmol. 2010;248:1313-7.2. Radcliffe NM, et al. Ophthalmic Surg Lasers Imaging. 2010;41:629-34.
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