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Abstract #9140 Published in IGR 5-2
Visualization of localized retinal nerve fiber layer defects with the GDx with individualized and with fixed compensation of anterior segment birefringence
Reus NJ; Colen TP; Lemij HGOphthalmology 2003; 110: 1512-1516
PURPOSE: To compare the visualization of localized retinal nerve fiber layer (RNFL) defects in GDx images with fixed and with individualized compensation of anterior segment birefringence (FC and IC, respectively) with their visualization in red-free fundus photographs. DESIGN: Observational case series. PARTICIPANTS: Eight eyes of six glaucoma patients with localized, wedge-shaped RNFL defects in red-free fundus photographs with matching visual field defects. METHODS: The authors imaged all eyes with a GDx equipped with a variable corneal compensator (VCC). The VCC replaced the standard fixed compensator and could be set to compensate for birefringence of up to 120 nm at any axis. Individual anterior segment birefringence was estimated from a macular retardation profile that resulted from the interaction between birefringence of the anterior segment and that of Henle's fiber layer. Measurements of RNFL retardation were made with the GDx with FC (60 nm of retardation with a slow axis of 15° nasally downward) and with IC. Maps of retardation measurements with FC and IC were superimposed on red-free fundus photographs. MAIN OUTCOME MEASURES: Visualization of localized RNFL defects. RESULTS: Localized RNFL defects were visible in GDx retardation maps obtained with IC. The defects closely matched those observed in red-free fundus photographs. With FC, however, the GDx retardation images did not correlate well with red-free fundus photography. CONCLUSIONS: An individualized anterior segment compensation in the GDx improves the visualization of localized glaucomatous loss.
Dr. N.J. Reus, Glaucoma Service, The Rotterdam Eye Hospital, P.O. Box 70030, NL-3000 LM Rotterdam, The Netherlands
Classification:
2.13 Retina and retinal nerve fibre layer (Part of: 2 Anatomical structures in glaucoma)
6.9.1 Laser scanning (Part of: 6 Clinical examination methods > 6.9 Computerized image analysis)
