title: Rat optic nerve head anatomy within 3D histomorphometric reconstructions of normal control eyes.
abstract: The purpose of this study is to three-dimensionally (3D) characterize the principal macroscopic and microscopic relationships within the rat optic nerve head (ONH) and quantify them in normal control eyes. Perfusion-fixed, trephinated ONH from 8 normal control eyes of 8 Brown Norway Rats were 3D histomorphometrically reconstructed, visualized, delineated and parameterized. The rat ONH consists of 2 scleral openings, (a superior neurovascular and inferior arterial) separated by a thin connective tissue strip we have termed the "scleral sling". Within the superior opening, the nerve abuts a prominent extension of Bruch's Membrane (BM) superiorly and is surrounded by a vascular plexus, as it passes through the sclera, that is a continuous from the choroid into and through the dural sheath and contains the central retinal vein (CRV), (inferiorly). The inferior scleral opening contains the central retinal artery and three long posterior ciliary arteries which obliquely pass through the sclera to obtain the choroid. Bruch's Membrane Opening (BMO) is irregular and vertically elongated, enclosing the nerve (superiorly) and CRV and CRA (inferiorly). Overall mean BMO Depth, BMO Area, Choroidal Thickness and peripapillary Scleral Thickness were 29 μm, 56.5 × 10(3) μm(2), 57 μm and 104 μm respectively. Mean anterior scleral canal opening (ASCO) and posterior scleral canal opening (PSCO) radii were 201 ± 15 μm and 204 ± 16 μm, respectively. Mean optic nerve area at the ASCO and PSCO were 46.3 × 10(3)±4.4 × 10(3) μm(2) and 44.1 × 10(3)±4.5 × 10(3) μm(2) respectively. In conclusion, the 3D complexity of the rat ONH and the extent to which it differs from the primate have been under-appreciated within previous 2D studies. Properly understood, these anatomic differences may provide new insights into the relative susceptibilities of the rat and primate ONH to elevated intraocular pressure.
authors.affiliation: Devers Eye Institute, Optic Nerve Head Research Laboratory, Legacy Research Institute, Portland, OR, USA; Hospital de l'Esperança, Parc de Salut Mar, Universitat Autònoma de Barcelona, Barcelona, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Pazos
authors.affiliation: Devers Eye Institute, Optic Nerve Head Research Laboratory, Legacy Research Institute, Portland, OR, USA.
authors.forename: Hongli
authors.initials: H
authors.lastname: Yang
authors.affiliation: Devers Eye Institute, Discoveries in Sight Research Laboratories, Legacy Research Institute, Portland, OR, USA.
authors.forename: Stuart K
authors.initials: SK
authors.lastname: Gardiner
authors.affiliation: Kenneth C. Swan Ocular Neurobiology Laboratory, Casey Eye Institute, Oregon Health and Science University, Portland, OR, USA.
authors.forename: William O
authors.initials: WO
authors.lastname: Cepurna
authors.affiliation: Kenneth C. Swan Ocular Neurobiology Laboratory, Casey Eye Institute, Oregon Health and Science University, Portland, OR, USA.
authors.forename: Elaine C
authors.initials: EC
authors.lastname: Johnson
authors.affiliation: Kenneth C. Swan Ocular Neurobiology Laboratory, Casey Eye Institute, Oregon Health and Science University, Portland, OR, USA.
authors.forename: John C
authors.initials: JC
authors.lastname: Morrison
authors.affiliation: Devers Eye Institute, Optic Nerve Head Research Laboratory, Legacy Research Institute, Portland, OR, USA. Electronic address: cfburgoyne@deverseye.org.
authors.forename: Claude F
authors.initials: CF
authors.lastname: Burgoyne
mesh_terms: D000818:Animals; D021621:Imaging, Three-Dimensional; D008297:Male; D008854:Microscopy, Electron / Q000379:methods; D009898:Optic Disk / Q000648:ultrastructure*; D051381:Rats; D011914:Rats, Inbred BN; D012016:Reference Values
keywords: Glaucoma; Neural canal; Optic nerve; Optic nerve head; Rat; Scleral canal