BackgroundTo examine histomorphometrically the parapapillary region in human eyes.Methodology/Principal FindingsThe histomorphometric study included 65 human globes (axial length:21–37 mm). On anterior-posterior histological sections, we measured the distance Bruch's membrane end (BME)-optic nerve margin (“Gamma zone”), BME-retinal pigment epithelium (RPE) (“Beta zone”), BME-beginning of non-occluded choriocapillaris, and BME-beginning of photoreceptor layer. “Delta zone” was defined as part of gamma zone in which blood vessels of at least 50 µm diameter were not present over a length of >300 µm. Beta zone (mean length:0.35±0.52 mm) was significantly (P = 0.01) larger in the glaucoma group than in the non-glaucomatous group. It was not significantly (P = 0.28) associated with axial length. Beta zone was significantly (P = 0.004) larger than the region with occluded choriocapillaris. Gamma zone (mean length:0.63±1.25 mm) was associated with axial length (P<0.001;r2 = 0.73) with an increase starting at an axial length of 26.5 mm. It was not significantly (P = 0.24) associated with glaucomatous optic neuropathy. Delta zone (present only in eyes with axial length of ≥27 mm) was associated with axial length (P = 0.001) and scleral flange length (P<0.001) but not with glaucoma (P = 0.73).Conclusions/SignificanceParapapillary gamma zone (peripapillary sclera without overlying choroid, Bruch's membrane and deep retinal layers) was related with axial globe elongation and was independent of glaucoma. Delta zone (no blood vessels >50 µm diameter within gamma zone) was present only in highly axially elongated globes and was not related with glaucoma. Beta zone (Bruch's membrane without RPE) was correlated with glaucoma but not with globe elongation. Since the region with occluded choriocapillaris was smaller than beta zone, complete loss of RPE may have occurred before complete choriocapillaris closure.

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Background: To examine histomorphometrically the parapapillary region in human eyes.

ABSTRACT.Purpose: 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. Methods: 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. Results: 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 lm; p = 0.29), optic disc border (281 ± 103 versus 391 ± 170 lm; p = 0.07), optic disc centre (1059 ± 191 versus 978 ± 205 lm; p = 0.30) and retrobulbar cerebrospinal fluid space (173 ± 58 versus 172 ± 81 lm; p = 0.97) nor in the minimal PACZH diameter (39 ± 18 versus 36 ± 18 lm; p = 0.74) and maximal PACZH diameter (78 ± 37 versus 65 ± 25 lm; 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). Conclusions: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.