Scanning laser polarimetry: logistic regression analysis for perimetric glaucoma diagnosis

Abstract

Purpose To calculate and validate a linear discriminant function (LDF) for scanning laser polarimetry (SLP) with variable corneal compensation (GDx-VCC) to increase the diagnostic accuracy when using isolated retinal nerve fibre layer (RNFL) parameters to discriminate between healthy and glaucomatous eyes with visual field loss. Methods We prospectively selected two independent samples (teaching and validating sets). The teaching set, comprising 71 consecutive healthy subjects and 73 patients with open-angle glaucoma, was used to calculate the LDF. The validating set, comprising 72 consecutive normal eyes and 76 glaucoma patients, was used to test the performance of the LDF in an independent population. Receiver operating characteristic (ROC) curves were plotted for the validating set to evaluate the diagnostic accuracy of the LDF and the SLP parameters. Results The obtained function was LDF ¼ À12.20 þ (0.15 Â nasal average)À(23.85 Â normalized inferior area) þ (1.18 Â maximum modulation). The areas under the ROC curve were 0.901 and 0.893 for our LDF and 0.893 and 0.877 for the nerve fibre indicator (NFI) in the teaching and validating populations, respectively. There were no significant differences between these values (P ¼ 0.743 in the teaching set, and P ¼ 0.458 in the validating set). NFI was the SLP-provided parameter with the best sensitivity-specificity balance. Sensitivities were 57.89% for the LDF and 48.68% for NFI at 95% fixed specificity. Conclusions The LDF and NFI were the most accurate SLP parameters for diagnosing glaucoma. The LDF yielded the highest sensitivity at 95% fixed specificity to discriminate between normal and glaucoma subjects.

Assessment of the retinal nerve fiber layer in individuals with obstructive sleep apnea

“…NFI ranges from 1 to 100, with lower values (around <25) indicating normal RNFL. Although some studies indicate that the NFI is the most sensitive parameter of SLP for glaucoma diagnosis [ 39 , 40 ], its calculation method is based on various parameters and therefore it does not directly indicate RNFL thickness.…”

Repeatability and Reproducibility of Retinal Nerve Fiber Layer Parameters Measured by Scanning Laser Polarimetry with Enhanced Corneal Compensation in Normal and Glaucomatous Eyes

“…SLP parameters included in the statistical analysis were nerve fiber indicator (NFI), temporal-superior-nasal-inferior-temporal (TSNIT) average, superior average, inferior average, and TSNIT standard deviation. Although some studies indicate that the NFI is the most sensitive parameter of SLP for glaucoma diagnosis [ 10 , 11 ], its calculation method is based on various parameters and the result does not directly indicate RNFL thickness.…”