Glaucomatous progression in the retinal nerve fibre and retinal ganglion cell-inner plexiform layers determined using optical coherence tomography-guided progression analysis.

Background: To investigate the characteristics of glaucomatous progression in circumpapillary retinal nerve fibre layer (RNFL) and macular retinal ganglion cell-inner plexiform layer (GCIPL) determined using optical coherence tomography-guided progression analysis (OCT-GPA). Methods: Serial OCT images of 527 glaucomatous eyes with greater than four OCT tests were screened. Among them, 106 (20.1 per cent) eyes with progression in either RNFL or GCIPL determined using OCT-GPA were included. Based on the agreement of progression detection between RNFL and GCIPL, the eyes were classified into the 'RNFL progression earlier group', 'GCIPL progression earlier group', or 'simultaneous progression group'. The type of progression was classified as diffuse, localised or mixed. Results: Among the 106 eyes with progression, 100 (94.3 per cent) showed RNFL progression and 83 (78.3 per cent) showed GCIPL progression. Fifty-four (50.9 per cent), 13 (12.3 per cent), and 39 (36.8 per cent) eyes were classified into the RNFL progression earlier group, GCIPL progression earlier group, and simultaneous progression group, respectively. Diffuse-type progression was found in three (three per cent) eyes with RNFL progression and 32 (38.6 per cent) eyes with GCIPL progression. The most common location of progression was the 7 o'clock sector (42.0 per cent) in the RNFL and the inferotemporal sector (39.8 per cent) in the GCIPL. Conclusions: The most common characteristic of RNFL and GCIPL progression determined using OCT-GPA was localised thinning in the inferotemporal area. Progression was more frequently found in the RNFL than in the GCIPL, and diffuse-type progression was more frequent in the GCIPL than in the RNFL.