A small disc size, a big challenge: effect of optic disc size on the correlation between peripapillary choroidal thickness, peripapillary retinal nerve fiber layer, and ganglion cell layer.

Purpose: We aimed to analyze the effect of optic disc size on the correlation between the peripapillary choroid (PPC), peripapillary retinal nerve fiber layer (RNFL), and macular ganglion cell inner plexiform layer (MGCIPL) thicknesses in subjects with ocular hypertension (OHT) and primary open angle glaucoma (POAG).

Methods: This study included 61 eyes with a disc area (DA) of ≤ 1.63 mm², 92 eyes with a DA of 1.63-2.42 mm², and 59 eyes with a DA of ≥ 2.42 mm² in small disc, regular disc, and large disc groups, respectively. The swept-source optical coherence tomography scans of the PPC, RNFL, and MGCIPL were analyzed according to disc size.

Results: The three groups did not significantly differ in RNFL or MGCIPL measurements, but the PPC measurement was statistically significantly higher in the small disc group and statistically significantly thinner in the large disc group. Most of the correlations observed between the RNFL and MGCIPL measurements and eye characteristics in the regular disc group were not detected in the small and large disc groups. While the RNFL and MGCIPL were well correlated in all disc size groups, the PPC did not correlate with the RNFL or MGCIPL in any of the groups.

Conclusions: Overall, the RNFL and MGCIPL measurements were consistent across all three disc sizes. While the PPC was thicker in small discs than in larger discs, it was not correlated with the RNFL or MGCIPL.