Scanning Laser Polarimetry With Variable Corneal Compensation And Optical Coherence Tomography In Normal And Glaucomatous Eyes

Abstract

Abstract: : Purpose: To evaluate the relationship between visual function and retinal nerve fiber layer (RFNL) measurements obtained with scanning laser polarimetry with variable corneal compensation (SLP-VCC) and optical coherence tomography (OCT). Methods: The GDx Nerve Fiber Analyzer was modified to enable the measurement of corneal polarization axis and magnitude so that compensation for corneal birefringence was eye specific. Complete examination, SLP with fixed corneal compensation (FCC) and variable corneal compensation (VCC), and automated achromatic perimetry (AAP) were performed in all subjects. Exclusion criteria were visual acuity <20/40, diseases other than glaucoma and unreliable AAP. Results: 59 eyes of 59 patients (29 normal, 30 glaucomatous) were enrolled (mean age 56.7 ± 20.3 years, 20-91). All eyes with glaucoma had associated visual field loss (average MD -8.4 ± 5.8 dB). Compared with FCC, the following retardation parameters generated with SLP-VCC showed a greater correlation with visual field MD: average thickness (R₂ = 0.06 for FCC, R₂ = 0.12 for VCC), ellipse average (R₂ = 0.12, R₂ = 0.28), superior average (R₂ = 0.17, R₂ = 0.27), inferior average (R₂ = 0.2, R₂ = 0.27), and superior integral (R₂ = 0.08, R₂ = 0.25). Compared with FCC, the same retardation parameters obtained with SLP-VCC showed increased correlation with OCT-derived RFNL thickness: (R₂ = 0.01, R₂ = 0.05), (R₂ = 0.04, R₂ = 0.19), (R₂ = 0.08, R₂ = 0.31), (R₂ = 0.10, R₂ = 0.20), and (R₂ = 0.04, R₂ = 0.25), respectively. Conclusion: Compared with fixed compensation, structural measurements generated with SLP-VCC have greater correlation with visual function and RFNL thickness assessments obtained with OCT.

Keywords: 430 imaging/image analysis: clinical