Comparison of Retinal Nerve Fiber Layer Measurements between NTG and HTG using GDx-VCC

PURPOSE To compare quantitative polarimetric measurements in eyes with NTG and HTG using GDx-VCC. Both groups were matched by age and glaucoma stage based on the Humphrey visual field test. METHODS We retrospectively reviewed the records of 146 patients who underwent Humphrey field analysis (HFA) and GDx-VCC. We compared outcomes of retinal nerve fiber layer (RNFL) parameters among the three groups by ANOVA and between each pair of groups using the Tukey-Kramer Post-Hoc test. We also evaluated the sensitivity and specificity of GDx-VCC in detecting glaucoma in each group. RESULTS The mean age and HFA mean deviation (MD) were 55.6 +/- 9.5 years and -0.8 +/- 1.5 dB in 47 control patients, 59.4 +/- 9.0 years and -5.77 +/- 4.38 dB in 49 NTG patients, and 59.4 +/- 11.7 years and -8.09 +/- 6.77 dB in 51 HTG patients, respectively. All thickness parameters were lower in HTG patients compared to NTG patients, but there were no significant differences in ratio parameters between age-matched early HTG and NTG patients. The sensitivity of GDx-VCC was significantly higher in both early and total HTG patients compared to the respective groups of NTG patients. CONCLUSIONS Compared to eyes with NTG, eyes with HTG showed reduced RNFL thickness and ratio parameters when patients were age and visual field matched. GDx-VCC appeared to be more sensitive in detecting RNFL damage in HTG patients.