SCANNING LASER POLARIMETRY AND CORRELATION WITH AUTOMATED PERIMETRY IN GLAUCOMA DIAGNOSIS

Purpose To compare scanning laser polarimetry GDx (Carl Zeiss Meditec Inc.) with variable corneal compensation (VCC) vs enhanced corneal compensation (ECC) (fig.1) and to correlate GDX structural data with functional data of Standard Automated Perimetry (SAP). Methods 339 eyes of 182 patients (tab. 1) were included and screened by the glaucoma unit of the University Eye Clinic of Pavia (Italy). Patients were submitted to complete ophthalmic examination, standard automated perimetry (SAP), scanning laser polarimetry with GDx- VCC and GDx-ECC. Quality image (Q), typical scan score (TSS), nerve fibers index (NFI), nerve fibers layer average thickness in a band around the optic nerve head (TSNIT average) and in the upper (TSNIT sup) and lower sector (TSNIT inf) provided by VCC and ECC were taken into account and compared using Wilcoxon signed-rank test. Correlation between GDx and perimetric global indexes MD, PSD and Glaucoma Staging System 2 was evaluated with Pearson correlation index (r). The same statistics were applied to a smaller group of 118 eyes characterized by a scanning laser polarimetry of optimal quality (Q>7 and TSS>80 with VCC and ECC). Results ECC provides better quality images than VCC: 204 images out of 339 (60%) were of good quality (Q>7) with VCC and 325 out of 339 (96%) with ECC (fig. 2). 140 images out of 339 (41%) were atypical (TSS