Progression Detection in Advanced Glaucoma Eyes with Non-Progressing Ganglion Cell-Inner Plexiform Layer.

Abstract

Purpose : Macular ganglion cell-inner plexiform layer (GCIPL) measurement with OCT has been suggested as an alternative for detecting progression in advanced stages of glaucoma. In this study we evaluated if conventional optic nerve head (ONH) and visual field (VF) parameters could be used to detect progression in eyes with advanced structural damage, in which the GCIPL approaches the practical minimal measurable level (floor effect).

Methods : Subjects with advanced structural glaucoma (average circumpapillary retinal nerve fiber layer (cRNFL) thickness ≤60µm) with ≥ 4 visits with qualified perimetry (Humphrey Field Analyzer; Zeiss) and spectral-domain OCT (Cirrus HD-OCT; Zeiss) were enrolled. Subjects were divided into Change or No change groups based on their GCIPL findings on macular guided progression analysis (GPA). No change was defined as: no change >2μm in average, superior or inferior GCIPL between the first and last visits, no statistically significant rate of change, and no cluster marking change in deviation maps in any visits. Structural (cRNFL, GCIPL and ONH) and functional (VF mean deviation (MD) and visual field index (VFI)) parameters were analyzed using a hierarchical linear model adjusting for eye correlation within subjects. Covariates included were age, ethnicity, signal strength, inclusion in No change group, follow-up duration and its interaction with the No change group.

Results : 44 eyes (37 subjects) qualified for the study with 22 eyes (50%) in each group. The average age at baseline was 67.0±11.4 years and mean follow-up was 4.1±1.8 years. The Change group had significantly thicker average, superior and inferior GCIPLs compared to the No change group at baseline (Table 1). Longitudinal analysis showed significant rates of change for most parameters in the Change group (Table 2). In the No change group, no significant thinning of the cRNFL was detected whereas VF and ONH parameters (Cup/Disc ratios and cup volume) showed significant change.

Conclusions : Eyes with advanced glaucomatous structural damage approaching the presumable GCIPL floor effect on OCT demonstrated changes in ONH and VF parameters even when no further RNFL thinning was detected. Novel parameters for evaluating ONH structure may be useful in the follow-up of advanced glaucoma.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.