The Pattern of Retinal Nerve Fiber Layer and Macular Ganglion Cell-Inner Plexiform Layer Thickness Changes in Glaucoma

Abstract

Background/aims: To investigate the patterns of retinal ganglion cell damage at different stages of glaucoma, using the circumpapillary retinal nerve fiber layer (RNFL) and macula ganglion cell-inner plexiform layer (GCIPL) thicknesses.

Methods: In 296 eyes of 296 glaucoma patients and 55 eyes of 55 healthy controls, the correlations of mean deviation (MD) with the superior and inferior quadrant RNFL/GCIPL thickness (defined as the average of three superior and inferior sectors, resp.) were analyzed.

Results: In early to moderate glaucoma, most of the RNFL/GCIPL thicknesses had significant positive correlations with the MD. In advanced glaucoma, the superior GCIPL thickness showed the highest correlation with MD (r = 0.495), followed by the superior RNFL (r = 0.452) (all; P < 0.05). The correlation coefficient of the inferior RNFL thickness with MD (r < 0.471) was significantly stronger in early to moderate glaucoma compared to that in advanced glaucoma (r = 0.192; P < 0.001). In contrast, the correlations of the superior GCIPL thickness with MD (r = 0.452) in advanced glaucoma was significantly stronger compared to that in early to moderate glaucoma (r = 0.159; P < 0.001).

Conclusions: The most preserved region in advanced glaucoma appears to be the superior macular GCIPL, whereas the most vulnerable region for initial glaucoma is the inferior RNFL around the optic disc.

Figure 1

Scatterplot showing the average, superior, and inferior cpRNFL/GCIPL thicknesses according to glaucoma severity assessed using mean deviation (MD) in the study population.

Figure 2

Comparisons of the superior and inferior cpRNFL/GCIPL thickness in healthy controls, in early, moderate, and advanced glaucomatous eyes. ^∗P < 0.05.

Figure 3

Correlation coefficients for the MD from the Humphrey visual field analysis with the cpRNFL and GCIPL sectoral parameters by OCT in glaucomatous eyes at different stages. ^∗P < 0.05.

Figure 4

Average threshold sensitivity maps of the advance glaucoma subgroups (I to V) in cross-sectional analysis. The grayscale applied is shown on the top left. With increasing disease severity, the deepening and enlargement of scotomas occurred more frequently in superior hemifield. The scotomas in both hemifields spread toward the physiologic blind spot and toward the nasal periphery in an arcuate pattern. The scotomas in superior hemifield occurred very closely to the area corresponding to the papillomacular bundle, whereas the parafoveal area of inferior hemifield was relatively spared (a). With the disease severity (I to V), superior RNFL and superior GCIPL thickness became significantly thinner (P = 0.003 and 0.005, resp.), whereas changes of inferior RNFL and inferior GCIPL were not significant (P = 0.505 and 0.109, resp.) (b and c). “X” indicates blind spot; dB = decibel.