Evaluation of Retinal Nerve Fiber Layer and Macular Ganglion Cell Layer Thickness in Relation to Optic Disc Size

To investigate whether optic nerve ganglion cell amount is dependent on optic disc size, this trial analyzes the correlation between Bruch's membrane opening area (BMOA) and retinal nerve fiber layer (RNFL) thickness as well as macular ganglion cell layer thickness (mGCLT). Additionally, differences in RNFL and mGCLT regarding various optic disc cohorts are evaluated. This retrospective, monocentric study included 501 healthy eyes of 287 patients from the University Hospital Munster, Germany, who received macular and optic disc optical coherence tomography (OCT) scans. Rank correlation coefficients for clustered data were calculated to investigate the relationship between BMOA and thickness values of respective retinal layers. Furthermore, these values were compared between different optic disc groups based on BMOA. Statistical analysis did not reveal a significant correlation between BMOA and RNFL thickness, nor between BMOA and mGCLT. However, groupwise analysis showed global RNFL to be significantly decreased in small and large discs in comparison to medium discs. This was not observed for global mGCLT. This study extends existing normative data for mGCLT taking optic disc size into account. While the ganglion cell amount represented by the RNFL and mGCLT seemed independent of BMOA, mGCLT was superior to global RNFL in displaying optic nerve integrity in very small and very large optic discs.

Automated summary

This study investigates the correlation between Bruch's membrane opening area (BMOA), retinal nerve fiber layer (RNFL) thickness and macular ganglion cell layer thickness (mGCLT) to determine if optic nerve ganglion cell amount is dependent on optic disc size. The results show no significant correlation between BMOA and RNFL thickness, nor between BMOA and mGCLT. However, groupwise analysis reveals decreased global RNFL in small and large discs compared to medium discs, while global mGCLT is not affected. This study provides extended normative data for mGCLT considering optic disc size and suggests that mGCLT is superior to global RNFL in indicating optic nerve integrity in very small and very large optic discs.