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X. Fan, L.-L. Wu, Z.-Z. Ma; Frequency-Doubling Technology in Perimetrically Normal Eyes of Open-Angle Glaucoma Patients With Unilateral Field Loss. Invest. Ophthalmol. Vis. Sci. 2010;51(13):5519.
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To determine whether frequency-doubling technology (FDT) perimetry detects visual field loss in perimetrically normal eyes of patients with open-angle glaucoma (OAG) and whether these visual field defects are subsequently detected by standard automated perimetry (SAP), and to explore the relating factors of the progression from abnormalities based on FDT to visual field loss based on SAP.
Perimetrically normal eyes of 68 OAG patients with unilateral field loss detected by SAP (Octopus, G2 program) were examined with the FDT N-30 threshold program. The visual field examination was followed by a series SAP examinations administered over 3 years. The relationship between FDT and subsequent SAP results in perimetrically normal eyes was analyzed. Glaucomatous optic neuropathy (GON), visual field indices, intraocular pressure (IOP), and central corneal thickness (CCT) were compared between "converters" (eyes with subsequent SAP abnormality) and "non-converters" within perimetrically normal eyes with abnormal FDT results. Finally, the SAP test points were matched to the abnormal FDT sectors. The relative risk (RR) of subsequent SAP abnormality corresponding to FDT abnormal sectors was calculated.
Sixty perimetrically normal eyes of 60 participants had complete data and a qualifying follow-up. Baseline FDT results were abnormal in 65%. Of the eyes with abnormal FDT results, 51% developed abnormal SAP results after 4 to 27 months, whereas none of the eyes with normal FDT results developed abnormal SAP results (p<0.05). In perimetrically normal eyes with abnormal FDT results, converters had a greater cup-to-disk ratio, more eyes with GON, larger and deeper cups, and worse FDT mean deviation than "non-converters" (p<0.05). IOP and CCT did not differ between the two groups. The RR of subsequent SAP abnormality corresponding to abnormal FDT sectors was 5.38 (95% confidence interval, 3.61-8.04, p<0.05).
In perimetrically normal eyes of OAG patients, FDT detected visual field loss in almost 2/3 of these eyes, and also predicted to some extent future visual field loss on SAP. Severity of glaucomatous neuropathy at baseline was related to conversion of abnormalities on FDT to visual field loss on SAP.
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