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Kamal Fahim, Anju Goyal, Daniel Hekman; The Significance of Non-Specific Visual Field Defects in the Evaluation of Glaucoma. Invest. Ophthalmol. Vis. Sci. 2011;52(14):5086.
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In the management of primary open angle glaucoma (POAG) or glaucoma suspects (GS), clinicians utilize Ocular Coherence Tomography (OCT) and Humphrey Visual Field (HVF) to evaluate the optic nerve. Clinicians face a quandary when evaluating POAG or GS patients with non-specific pattern defects on HVF. It is unclear if non-specific defects are a variation of normal or if they signify loss of nerve fiber layer thickness (NFLT). A correlation between HVF pattern defects with loss of NFLT on OCT has been demonstrated in the literature. Non-specific defects, however, are not clearly defined and have not been correlated to a structural defect. The purpose of this study is to determine whether or not non-specific HVF defects have a loss in NFLT as compared to normal HVF.
In this retrospective study, patients with the diagnosis of POAG or GS and at least 2 reliable and reproducible HVF and 1 reliable OCT were included. A reliable HVF was defined as having less than 25% fixation losses, false positive rate, and false negative rate. A reliable OCT was defined as signal strength of at least 6. Only eyes with normal HVF (Group 1) or non-specific HVF (Group 2) were included. Modeled after the Hodapp grading scale, a non-specific HVF was defined as 1 to 3 points depressed on the pattern deviation plot at the 2% level not in a glaucomatous pattern. A normal HVF was defined as a field with no points of depression on the pattern deviation plot at the 2% level. Total and quadrant NFLT were recorded.
128 eyes of 77 patients met the inclusion criteria. 55 eyes had normal HVF (Group 1) and 73 eyes had non-specific HVF (Group 2). Mean age was 60 years old for Group 1 and 63 years old for Group 2. In Group1, the mean total NFLT was 99.9 microns (84-138). The mean superior quadrant NFLT was 122.7 microns, the mean temporal quadrant NFLT was 66.8 microns, the mean inferior quadrant NFLT was 125.8 microns, and the mean nasal quadrant NFLT was 81.2 microns. In Group 2, the mean total NFLT was 78.9 microns (61-98), the mean superior quadrant NFLT was 93.8 microns, the mean temporal quadrant NFLT was 58.7 microns, the mean inferior quadrant NFLT was 101.8 microns, and the mean nasal quadrant NFLT was 61.5 microns. Group 2 had statistically significant total NFLT thinning as compared to Group 1 (P< 0.01).
In the management of POAG and GS, the significance of non-specific HVF is often overlooked. Our results suggest that reliable and reproducible non-specific defects on HVF correlates with NFLT loss. Patients with non-specific defects on HVF may need to be followed more closely and managed more aggressively than previously thought.
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