Scanning laser polarimetry with enhanced corneal compensation in patients with open-angle glaucoma.

Aims

To compare the retinal nerve fiber layer thickness (RNFLT) parameters obtained with newly introduced GDx with enhanced corneal compensation (ECC) and those with GDx with variable corneal compensation (VCC) and to evaluate their reproducibility and the correspondence with visual field damage (VFD) in total or sectorized fields in association with refractive errors in open-angle glaucoma (OAG) patients.

Patients and methods: Measurement reproducibility was assessed in 30 normal and 30 OAG eyes. Correlation between the RNFLT parameters and the corresponding VFD was evaluated in 58 OAG eyes.

Results

All parameters of both GDx VCC and ECC showed high intraclass correlation coefficients among the repeated measurements (0.89 to 0.99), suggesting good reproducibility. All RNFLT parameters were significantly correlated between VCC and ECC (intraclass correlation coefficient=0.58-0.92, P<0.001) though they were significantly different. In OAG eyes, correlation between temporal, superior, nasal, inferior, temporal average and mean deviation of VFD was similar in both algorithms (Rs=0.58 and 0.53, P<0.001). When the OAG eyes were subgrouped by refractive error at -5 D, the correlation was significant for both ECC and VCC in the lower myopic group (>-5 D) (Rs=0.71 and 0.74, P<0.0001) but was significant only for ECC in the higher myopic group (<or=-5 D) (ECC: Rs=0.44, P=0.016, VCC: Rs=0.19, P=0.309). In all 58 OAG eyes, significant correlation between the sectorized VFD and the corresponding RNFLT was found in the superior arcuate, inferior arcuate, and inferior para-arcuate areas for both VCC and ECC in the sector analysis (P<0.01), whereas the correlation was significant only for ECC (Rs=0.46, P<0.001) but not for VCC (Rs=0.30, P=0.024) in the superior para-arcuate.

Conclusions

The results of GDx ECC were well correlated with those of VCC and had good reproducibility equivalent to that of VCC. Introduction of the ECC algorithm should improve the correspondence with VFD at least in moderate to high myopic OAG patients.