When clinicians use OCT to evaluate glaucoma progression, they’re either focused on analyzing the progressive retinal nerve fiber layer (RNFL) thinning over the parapapillary region or else the progressive ganglion cell inner plexiform layer (GCIPL) thinning over the macula. But new research suggests that by combining the RNFL and GCIPL into a single layer (the RNFL-GCIPL), widefield progression analysis can outperform either single layer alone.

Their research shows that this combined analysis can reveal a significant portion of progressing eyes that neither progression analysis of RNFL thickness nor GCIPL thickness would identify. “Wide-field progression analysis of RNFL-GCIPL thickness is effective to inform the risk of visual field progression in glaucoma patients,” the study authors wrote in their paper.

To arrive at this conclusion, the investigators looked at 440 eyes from 236 glaucoma patients and 98 eyes from 49 healthy individuals. More (127) eyes showed progressive RNFL-GCIPL thinning than either progressive RNFL thinning (74 eyes) or progressive GCIPL thinning (26 eyes). Progressive RNFL-GCIPL thinning was almost always detected before or, at least simultaneously with, progressive thinning in either structure alone. After adjusting for covariates, the researchers found that eyes with progressive RNFL-GCIPL thinning had a higher risk to develop possible or likely visual field progression compared with eyes without progressive RNFL-GCIPL thinning, suggesting that combining these structures can work to identify change in glaucoma.

Wu K, Lin C, Lam A, et al. Wide-field trend-based progression analysis of combined retinal nerve fiber layer and ganglion cell inner plexiform layer thickness—a new paradigm to improve glaucoma progression detection. Ophthalmology. March 28, 2020. [Epub ahead of print].