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S.M. Walsman, P.J. Lama; Frequency and Characteristics of Non–Nerve Fiber Layer Polarization Artifact in African–American Patients Undergoing Scanning Laser Polarimetry With the GDX/VCC . Invest. Ophthalmol. Vis. Sci. 2005;46(13):4808.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To assess the frequency, describe the characteristics and clinically correlate atypical nerve fiber layer scans in African–American patients undergoing scanning laser polarimetry (SLP) with GDX/VCC analyzer. Methods: Retrospective consecutive case–series. Results: Ninety–one eyes of 46 patients of African–American origin underwent SLP with the GDX/VCC analyzer. (Laser Diagnostics Tech, Inc. San Diego) Eight patients were excluded from data analysis due to inadequate scan quality or incomplete clinical data. Of the remaining 38 patients, 14 had atypical scans in one or both eyes. Seventeen eyes had 1 or more focal areas of variable intensity non–nerve fiber layer polarization signals (NNFLPS) and 6 eyes had diffusely intense NNFLPS. Eight of the 14 patients subsequently underwent GDX/ECC (GDX with enhanced corneal compensation) to improve the diagnostic accuracy of the scans. All eyes had partial to near full correction of the abnormal signals with correspondingly improved diagnostic accuracy. The values of the SLP parameters were reduced in nearly all cases following GDX/ECC but NFI values changed unpredictably with some eyes having values increasing or decreasing by as much as 44 points. Clinical features in eyes with atypical scans revealed prominently visible or moderately visible choroidal vascular patterns in 12/14 patients while the other 2 patients had eyes with minimally visible or not visible choroidal vasculature. In addition, 6/14 patients had variable degrees of peripapillary atrophy in each eye. In contrast, the eyes of 18/24 patients with typical scans had minimally visible or not visible choroidal vasculature while 4/24 had moderately visible and 2/24 prominently visible choroidal vasculature. Peripapillary atrophy was seen in either or both eyes of 3/24 patients with typical scans. Conclusions: Individual corneal compensation has improved the diagnostic accuracy of SLP. However, atypical scans characterized by NNFLPS have been anecdotally described in patients following GDX/VCC. Atypical scans are felt to be less common in black patients due to increased fundus pigmentation. However, in our study, 36.8% of the African–American patients had an atypical scan in one or both eyes. The probability of having an atypical scan appears to be positively correlated with the visibility of the choroidal vasculature and presence of peripapillary atrophy.
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