Long-Term Reproducibility of Macular Ganglion Cell Analysis in Clinically Stable Glaucoma Patients

To investigate the long-term reproducibility of macular ganglion cell analysis in clinically stable glaucoma patients using spectral-domain optical coherence tomography (SD-OCT).

One hundred nine eyes of 109 clinically stable open-angle glaucoma patients with a localized retinal nerve fiber layer (RNFL) defect and a corresponding macular ganglion cell-inner plexiform layer (GCIPL) defect were included in this retrospective, longitudinal study. Clinical stability was defined as showing no change on serial structural (stereo-disc and RNFL photography) and functional (visual field progression analysis) assessments. Three serial SD-OCT (Cirrus-HD) peripapillary and macular scans taken at 6-month intervals were analyzed. Intraclass correlation coefficient (ICC), coefficient of variation (CV), test-retest standard deviation (TRTSD), and tolerance limit of area and angular width of GCIPL defect and GCIPL thickness measurements were assessed.

The ICC of the GCIPL thickness parameters ranged from 0.966 to 0.992, and the CV from 2.0% to 5.5%. The TRTSD was the lowest for the average GCIPL thickness (1.45 μm), the highest for the minimum GCIPL thickness (3.42 μm), and varied from 1.54 to 2.16 μm for the sectoral measurements. The ICC, CV, and TRTSD were 0.993, 3.9%, and 5.32° for angular width, and 0.930, 6.7%, and 0.27 mm2 for area of GCIPL defect. Measurement variances (TRTSD) for the GCIPL measurements showed no significant association with the glaucomatous severity.

The macular GCIPL thickness and deviation maps showed excellent long-term intervisit reproducibility. Macular ganglion cell analysis can be considered as an effective means of monitoring glaucomatous progression in macula.