Abstract
Abstract: :
Purpose:To determine the ability of scanning laser polarimetry (SLP) done by GDx to identify nerve fiber layer (NFL) defects in patients with focal visual field (VF) defects and focal notching of the optic nerve secondary to glaucoma. Methods:Retrospective chart review identified 41 eyes of 35 patients with reproducible (at least 2 VF tests done by SITA testing) focal VF defects in patients with glaucoma having no other cause for the defect and in whom the defect correlated with focal notching of the optic nerve, and who had SLP done with the GDx. We evaluated GDx color-coded thickness pictures, NFL contour profiles, 13 NFL analysis parameters, and also the "number" to determine the ability of GDx SLP to detect focal nerve defects. Results:Of the 41 eyes, 24 had superior focal VF defects and 17 had inferior focal VF defects. All had abnormal glaucoma hemifield tests. The average mean deviation was -5.34. The average number of contiguous abnormal testing points with probability of glaucoma change of p<0.5% on the pattern deviation plot was 10. Given these VF defects, 8 of the 41 eyes had no abnormal NFL analysis parameters. 5 of these 8 eyes had abnormal appearing NFL contour profiles that were all consistent with the VF defect. Of the 41 eyes, 37 contour profiles were judged abnormal and 4 were normal. 20 color thickness pictures were abnormal and 21 were judged normal. The "number" averaged 51 with a median of 49 and a range of 10 to 98. 9 eyes had a "number" less than 30 and 8 eyes had a "number" greater than 70. Of the 13 NFL analysis parameters, only superior/nasal (S/N) was abnormal in more than 50% of the appropriate eyes (11 of the 17 eyes with superior NFL defects). Inferior average was abnormal in 11 of 24 eyes with inferior NFL defects. No other single parameter identified a defect more than 25% of the time. Conclusion:SLP with GDx may miss many focal nerve defects (as evidenced by normal NFL analysis parameters in 8 of 41 eyes with focal defects). The "number" and the color thickness pictures were not helpful in identifying eyes with focal defects. Only one NFL analysis parameter identified abnormal eyes more than 50% of the time (S/N was abnormal in 11 of 17 eyes with superior defects). The contour profile was the most sensitive at identifying focal defecs, being abnormal in 37 of 41 eyes, and abnormal in 5 of 8 eyes in which NFL analysis parameters did not detect the defect.
Keywords: 430 imaging/image analysis: clinical • 484 nerve fiber layer • 432 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)