Abstract
Purpose :
To assess dimensions and associations of the peripapillary border tissue of the choroid (PBT-C) and peripapillary scleral flange (PBT-S) within the optic nerve head region
Methods :
The histomorphometric investigation included histologic sections of enucleated eyes of Caucasian patients. Using a light microscope, we measured the PBT dimensions.
Results :
The study included 85 eyes (85 patients) with a mean age of 62.0±14.1 years (range:37-87 years) and mean axial length of 26.7±3.5 mm (range:21.0-37.0 mm). Thicker PBT-C thickness (mean:68.1±36.0µm) was associated with shorter axial length (P<0.001; regression coefficient r:-0.52). Longer PBT-C length (mean:531±802µm) was correlated with longer axial length (P<0.001;r:0.66). PBT-C cross-sectional area (18869±13839µm2) was not significantly associated with axial length (P=0.37). The angle between PBT-C and Bruchs membrane (mean:80±53°) decreased with longer axial length (P<0.001;beta:0.70). In non-highly myopic eyes without overhanging Bruchs membrane, the angle was approximately 90°, in eyes with Bruchs membrane overhanging into the intrapapillary region, the angle ranged between 100° and 180°, and in eyes with parapapillary gamma zone, the angle was close to 0°. Thickness of PBT-S (mean:83.0±21.3µm) was correlated neither with axial length (P=0.28) or glaucoma (P=0.17). Optic nerve pia mater thickness (mean:109±44µm) increased with the glaucoma presence (P=0.007;beta:0.41) but not with axial length (P=0.45).
Conclusions :
PBT-C and PBT-S as continuation of the optic nerve pia mater are distinct structures with the PBT-C re-modelling with longer axial length and the PBT-S being independent of axial elongation. PBT-C and PBT-S may be of importance for the optic nerve head biomechanics and separation of the choroidal space from the intrapapillary compartment.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.