Scanning laser polarimetry in glaucoma suspects: influence of the lens

AbstractPurpose to compare scanning laser polarimetry (GDx) variable corneal compensation (VCC) and enhanced corneal compensation (ECC) in glaucoma suspects divided on the basis of lens conditionsMethods 339 eyes of 182 consecutive patients were selected and submitted to complete ophthalmic evaluation, automated perimetry (HFA 24‐2), scanning laser polarimetry of RNFL with GDx VCC and ECC. Patients were divided into 4 groups if pseudophakic (IOL) or with different lens opacities graded according to LOCS‐III (NO/NC 1, 2 or 3). Morphometric parameters as TSNIT average, superior, inferior, nerve fiber indicator(NFI); quality of the image (Q)and typical scan score(TSS) given by the two GDx algorithms were compared applying Wilkoxon signed‐rank test and Lin’s concordance coefficient. Kruskall‐Wallis test was used to compare the 4 groups on the basis of age, intra‐ocular pressure (IOP), perimetric indices as mean defect (MD) and pattern standard deviation (PSD),TSNIT,NFI,Q and TSSResults IOL group was significantly older, with lower IOP and higher MD as compared to the other groups. ECC gave better quality scans, thinner RNFL and higher NFI as compared to VCC. ECC/VCC outcomes were significantly different and concordance was poor to moderate but slightly better with transparent lens than with cataract (NO/NC3) or IOL. IOL and cataract seemed to affect GDx outcomes especially with VCCConclusion different lens conditions seemed to influence laser polarimetry outcomes particularly with VCC. ECC as compared to VCC gave better quality scans, thinner RNFL, higher NFI and was less influenced by lens condition. ECC could possibly better reproduce RNFL thickness, giving a more reliable model of early glaucomatous neuropathy