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1From the Department of Biomedical Engineering, Tulane University, New Orleans, Louisiana; the 3Devers Eye Institute, Legacy Health System, Portland, Oregon; the 4Department of Ophthalmology, University of Alabama, at Birmingham, Birmingham, Alabama; the 5Singapore Eye Research Institute (SERI), Singapore National Eye Center, Singapore; 6Third Eye Associates, Camden, New Jersey; and the 7School of Public Health, Louisiana State University Health Sciences Center, New Orleans, Louisiana.
PURPOSE. To delineate three-dimensionally the anterior and posterior surfaces of the lamina cribrosa, scleral flange, and peripapillary sclera, to determine the position and thickness of these structures within digital three-dimensional (3-D) reconstructions of the monkey optic nerve head (ONH).
METHODS. The trephinated ONH and peripapillary sclera from both eyes of three monkeys with early glaucoma (EG; one eye normal, one eye given laser-induced EG) were serially sectioned at 3-µm thickness, with the embedded tissue blocks face stained and imaged after each cut. Images were aligned and stacked to create 3-D reconstructions, within which Bruchs membrane opening (BMO) and the anterior and posterior surfaces of the lamina cribrosa and peripapillary sclera were delineated in 40 serial radial (4.5° interval) digital sagittal sections. For each eye, a BMO zero reference plane was fit to the 80 BMO points, which served as the reference from which all position measurements were made. Regional laminar, scleral flange, and peripapillary scleral position and thickness were compared between the normal and EG eyes of each monkey and between treatment groups by analysis of variance.
RESULTS. Laminar thickness varied substantially within the normal eyes and was profoundly thicker within the three EG eyes. Laminar position was permanently posteriorly deformed in all three EG eyes, with substantial differences in the magnitude and extent of deformation among them. Scleral flange and peripapillary scleral thickness varied regionally within each normal ONH with the scleral flange and peripapillary sclera being thinnest nasally. Overall, the scleral flange and peripapillary sclera immediately surrounding the ONH were posteriorly displaced relative to the more peripheral sclera.
CONCLUSIONS. Profound fixed posterior deformation and thickening of the lamina are accompanied by mild posterior deformation and thinning of the scleral flange and peripapillary sclera at the onset of confocal scanning laser tomography (CSLT)–detected ONH surface change in young adult monkey eyes with early experimental glaucoma.
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