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H. Yang, J.C. Downs, R.T. Hart, C.F. Burgoyne; Neural Canal and Peripapillary Scleral Alterations Within Three–Dimensional (3D) Reconstructions of Early Glaucoma (EG) Monkey Optic Nerve Heads (ONH) . Invest. Ophthalmol. Vis. Sci. 2005;46(13):3511.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To 3–dimensionally delineate the neural canal (Bruch’s membrane opening (BMO), anterior sclera canal opening (ASCO), anterior laminar insertion (ALI), and posterior laminar insertion (PLI)), relative to the anterior–most subarachnoid space (ASAS) within digital 3D reconstructions of the monkey ONH so as to test the hypothesis that there is a predictable pattern of EG deformation. Methods: 3D ONH reconstructions from the normal (N) and EG eyes of three young adult (age 8 years) EG monkeys (Burgoyne, et al, IOVS, 2004; 45:4378) were digitally overlaid onto clinical stereo photos to ensure accurate orientation. Using custom software, BMO, ASCO, ALI, PLI, and ASAS points were delineated within radial (interval), digital, sagittal sections. For each eye, BMO points were used to fit a least–squares ellipse and establish a BMO–centroid and BMO–zero reference plane (ZRP) upon which all ASCO, ALI, PLI and ASAS points were projected. For each parameter, for each region, the averaged distance from the projected points to the BMO–centroid (offset) and ZRP (depth) were calculated and compared between the N and EG eyes of each monkey, and between the pooled N and EG eyes overall, by ANOVA. Results: Considering all 3 monkeys together, all four neural canal parameters were significantly expanded (p<0.0001) in EG eyes; radial expansion of the canal was greatest posteriorly (PLI>ALI>ASCO>BMO) and most prominent inferiorly and superiorly; and posterior deformation of the PLI was greatest within the inferior temporal and superior nasal regions. Co–localized increases in PLI offset and depth (neural canal elongation) were present inferior–temporally in all 3 monkeys. ASAS was anteriorly displaced within the temporal and superior–temporal regions in all 3 EG eyes. Conclusions: Permanent deformation (expansion and elongation) of the neural canal and anteriorization of the subarachnoid space (possible splitting of the peripapillary sclera) are present in young adult EG monkey eyes at the onset of CSLT–detected ONH surface change.
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