Histomorphometry of the circular peripapillary arterial ring of Zinn–Haller in normal eyes and eyes with secondary angle‐closure glaucoma

Abstract

To examine the location and size of the peripapillary arterial circle of Zinn-Haller (PACZH) and its associations with other eye measures in normal eyes and eyes with secondary angle-closure glaucoma. The study included 29 human globes enucleated because of malignant choroidal melanoma (n = 19) (control group) or because of secondary angle-closure glaucoma (n=10). Anterior-posterior histological sections were morphometrically evaluated. The PACZH was present in all eyes. The glaucoma group and the control group did not vary significantly in the distance from the PACZH to Bruch's membrane (297 ± 67 versus 270 ± 67 μm; p = 0.29), optic disc border (281 ± 103 versus 391 ± 170 μm; p=0.07), optic disc centre (1059 ± 191 versus 978 ± 205μm; p = 0.30) and retrobulbar cerebrospinal fluid space (173 ± 58 versus 172 ± 81 μm; p = 0.97) nor in the minimal PACZH diameter (39± 18 versus 36 ± 18 μm; p = 0.74) and maximal PACZH diameter (78 ±37 versus 65 ± 25 μm; p = 0.36). The PACZH location, measured as distance from Bruch's membrane, disc border, disc centre and cerebrospinal fluid space, was not significantly associated with axial length (p > 0.39), horizontal globe diameter (p > 0.17) and vertical globe diameter (p > 0.22). Both diameters were statistically independent of axial length (p = 0.72 and p = 0.58, respectively), horizontal globe diameter (p = 0.60 and p = 0.41, respectively) and vertical globe diameter (p = 0.64 and p = 0.52, respectively). All parameters were statistically independent of age (p > 0.10) and gender (p > 0.10). The PACZH was present in all human eyes examined and did not vary significantly in location and diameter between eyes with secondary angle-closure glaucoma and nonglaucomatous eyes, nor between myopic versus hyperopic eyes.