Discrimination between normal and glaucomatous eyes with visual field and scanning laser polarimetry measurements

Aim-To evaluate the ability of structural parameters las determined by reti nal nerve fibre layer (RNFL) measurements obtained with the scanning laser polarimeter (SLP-NFA/GDx)) and functional parameters las determined by auto mated perimetry) to discriminate between normal and glaucomatous eyes. Methods-In a case-control study, a total of 91 normal subjects and 94 patie nts with glaucoma underwent automated perimetry and RNFL measurements obtai ned with the SLP. Three independent scans of each eye were obtained and a m ean image was created and used for further analysis. Only one eye per indiv idual was randomly included in the study. The sensitivity (Se) and specific ity (Sp) of 12 RNFL parameters were calculated according to the SLP interna l normative database. The Se and Sp of the visual field (VF) global indices and the glaucoma hemifield test (GHT) were also calculated according to th e instrument's normative database. Receiver operator characteristic (ROC) c urves were built for each SLP parameter and VF index. Fisher's linear discr iminant formulas (LDFs) were developed for VF indices (VF LDF), SLP measure ments (SLP LDF), and both examinations (combined LDF). Results-According to the SLP internal database, the parameters with better Se and Sp were: superior/nasal ratio (Se = 58.5%; Sp = 86.8%), and GDx the number (Se = 43.3%; Sp = 96.7%). The construction of an ROC curve for the n umber resulted in Se = 84% and Sp = 79%. The creation of LDFs improved both the sensitivities and specificities when compared with isolated parameters SLP LDF (Se = 90.4%; Sp = 82.4%), VF LDF (Se = 89.4%; Sp = 89.0%), and com bined LDF (Se = 93.0%; Sp = 90.1%). The sensitivity to diagnose early and m oderate glaucomatous damage observed with the GHT was lower than that obtai ned with the number (p < 0.01). Conclusions-Creation of LDFs enhanced the Se and Sp for both VF and SLP. In tegration of SLP and VF in a combined LDF reached the highest Se/Sp relatio n, suggesting that these examinations may be additive concerning the diagno sis of glaucoma. The SLP parameter the number may be more sensitive than th e GHT in diagnosing early and moderate glaucomatous damage.