Offset of openings in optic nerve head canal at level of Bruch’s membrane, anterior sclera, and lamina cribrosa
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SUBMITTER: Lee K
PROVIDER: S-EPMC8599705 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:PurposeCerebrospinal fluid pressure (CSFp) changes are involved or implicated in various ocular conditions including glaucoma, idiopathic intracranial hypertension, and visual impairment and intracranial pressure syndrome. However, little is known about the effects of CSFp on lamina cribrosa and retrolaminar neural tissue (RLNT) biomechanics, potentially important in these conditions. Our goal was to use an experimental approach to visualize and quantify the deformation of these tissues as CSFp increased.MethodsThe posterior eye and RLNT of porcine eyes (n = 3) were imaged using synchrotron radiation phase-contrast micro-computed tomography (PC μCT) at an intraocular pressure of 15 mm Hg and CSFps of 4, 10, 20, and 30 mm Hg. Scans of each tissue region were acquired at each CSFp step and analyzed using digital volume correlation to determine 3-dimensional tissue deformations.ResultsElevating CSFp increased the strain in the lamina cribrosa and RLNT of all three specimens, with the largest strains occurring in the RLNT. Relative to the baseline CSFp of 4 mm Hg, at 30 mm Hg, the lamina cribrosa experienced a mean first and third principal strain of 4.4% and -3.5%, respectively. The corresponding values for the RLNT were 9.5% and -9.1%.ConclusionsCSFp has a significant impact on the strain distributions within the lamina cribrosa and, more prominently, within the RLNT. Elevations in CSFp were positively correlated with increasing deformations in each region and may play a role in ocular pathologies linked to changes in CSFp.
| S-EPMC6733531 | biostudies-literature
Project description:PurposeTo measure the magnitude and direction of anterior scleral canal opening (ASCO) offset relative to the Bruch membrane opening (BMO) (ASCO/BMO offset) to characterize neural canal obliqueness and minimum cross-sectional area (NCMCA) in 69 highly myopic and 138 healthy, age-matched, control eyes.DesignCross-sectional study.MethodsUsing optical coherence tomography (OCT) scans of the optic nerve head (ONH), BMO and ASCO were manually segmented and their centroids and size and shape were calculated. ASCO/BMO offset magnitude and direction were measured after projecting the ASCO/BMO centroid vector onto the BMO plane. Neural canal axis obliqueness was defined as the angle between the ASCO/BMO centroid vector and the vector perpendicular to the BMO plane. NCMCA was defined by projecting BMO and ASCO points onto a plane perpendicular to the neural canal axis and measuring their overlapping area.ResultsASCO/BMO offset magnitude was greater (highly myopic eyes 264.3 ± 131.1 μm; healthy control subjects 89.0 ± 55.8 μm, P < .001, t test) and ASCO centroid was most frequently nasal relative to BMO centroid (94.2% of eyes) in the highly myopic eyes. BMO and ASCO areas were significantly larger (P < .001, t test), NCMCA was significantly smaller (P < .001), and all 3 were significantly more elliptical (P ≤ .001) in myopic eyes. Neural canal obliqueness was greater in myopic (65.17° ± 14.03°) compared with control eyes (40.91° ± 16.22°; P < .001, t test).ConclusionsOur data suggest that increased temporal displacement of BMO relative to the ASCO, increased BMO and ASCO area, decreased NCMCA, and increased neural canal obliqueness are characteristic components of ONH morphology in highly myopic eyes.
| S-EPMC9285095 | biostudies-literature
Project description:The lamina cribrosa likely plays an important role in retinal ganglion cell axon injury in glaucoma. We sought to (1) better understand optic nerve head (ONH) structure and anterior lamina cribrosa surface (ALCS) microarchitecture between fellow eyes of living, normal non-human primates and (2) characterize the time-course of in vivo structural changes in the ONH, ALCS microarchitecture, and retinal nerve fiber layer thickness (RNFLT) in non-human primate eyes with early experimental glaucoma (EG). Spectral domain optical coherence tomography (SDOCT) images of the ONH were acquired cross-sectionally in six bilaterally normal rhesus monkeys, and before and approximately every two weeks after inducing unilateral EG in seven rhesus monkeys. ONH parameters and RNFLT were quantified from segmented SDOCT images. Mean ALCS pore area, elongation and nearest neighbor distance (NND) were quantified globally, in sectors and regionally from adaptive optics scanning laser ophthalmoscope images. In bilaterally normal monkeys, ONH parameters were similar between fellow eyes with few inter-eye differences in ALCS pore parameters. In EG monkeys, an increase in mean ALCS Depth (ALCSD) was the first structural change measured in 6 of 7 EG eyes. A decrease in mean minimum rim width (MRW) simultaneously accompanied this early change in 4 of 6 EG eyes and was the first structural change in the 7th EG eye. Mean ALCS pore parameters were among the first or second changes measured in 4 EG eyes. Mean ALCS pore area and NND increased in superotemporal and temporal sectors and in central and peripheral regions at the first time-point of change in ALCS pore geometry. RNFLT and/or mean ALCS radius of curvature were typically the last parameters to initially change. Survival analyses found mean ALCSD was the only parameter to significantly show an initial change prior to the first measured loss in RNFLT across EG eyes.
| S-EPMC4521723 | biostudies-literature
Project description:BackgroundTo compare the lamina cribrosa between eyes with and without neovascular glaucoma (NVG) using enhanced depth imaging spectral-domain optical coherence tomography.MethodsForty-six patients with proliferative diabetic retinopathy were enrolled in this cross-sectional study. The patients were divided into two groups based on the absence or presence of NVG (the non-NVG group and the NVG group, respectively). The intraocular pressure (IOP), circumpapillary retinal nerve fiber layer (cpRNFL) thickness, anterior lamina cribrosa depth (ALD), and laminar thickness (LT) were compared between the groups.ResultsIn the non-NVG group, the mean age was 66.2 ± 2.4 (mean ± standard error) years, mean maximum IOP was 18.8 ± 1.8 mmHg, mean cpRNFL thickness was 91.2 ± 3.9 μm, mean ALD was 407.0 ± 22.9 μm, and mean LT was 155.0 ± 4.7 μm. In the NVG group, the mean age was 61.4 ± 2.1 years, mean maximum IOP was 33.1 ± 1.6 mmHg, mean cpRNFL thickness was 73.6 ± 3.4 μm, mean ALD was 403.9 ± 20.1 μm, and mean LT was 156.9 ± 4.2 μm. The IOP was significantly higher and the cpRNFL was significantly thinner in the NVG group (P < 0.001 and P = 0.002, respectively). However, the age, ALD, and LT were not statistically different between the groups (P = 0.151, 0.919, and 0.757, respectively).ConclusionsAlthough the cpRNFL was thinner, the structure of the lamina cribrosa was unchanged in the NVG eyes. Axonal loss of the retinal ganglion cells in NVG patients was prior to lamina cribrosa deformation.
| S-EPMC5407001 | biostudies-literature
Project description:This study investigated the inflation response of the lamina cribrosa (LC) and adjacent peripapillary sclera (PPS) in post-mortem human eyes with no history of glaucoma. The posterior sclera of 13 human eyes from 7 donors was subjected to controlled pressurization between 5-45 mmHg. A laser-scanning microscope (LSM) was used to image the second harmonic generation (SHG) response of collagen and the two-photon fluorescent (TPF) response of elastin within the volume of the LC and PPS at each pressure. Image volumes were analyzed using digital volume correlation (DVC) to calculate the three-dimensional (3D) deformation field between pressures. The LC exhibited larger radial strain, Err, and maximum principal strain, Emax, (p < 0.0001) and greater posterior displacement (p=0.0007) compared to the PPS between 5-45 mmHg, but had similar average circumferential strain, Eθθ, and maximum shear strain, Γmax. The Emax and Γmax were highest near the LC-PPS interface and lowest in the nasal quadrant of both tissues. Larger LC area was associated with smaller Emax in the peripheral LC and larger Emax in the central LC (p ≤ 0.01). The Emax, Γmax, and Eθθ in the inner PPS increased with increasing strain in adjacent LC regions (p ≤ 0.001). Smaller strains in the PPS were associated with a larger difference in the posterior displacement between the PPS and central LC (p < 0.0001 for Emax and Err), indicating that a stiffer pressure-strain response of the PPS is associated with greater posterior bowing of the LC. STATEMENT OF SIGNIFICANCE: Glaucoma causes vision loss through progressive damage of the retinal ganglion axons at the lamina cribrosa (LC), a connective tissue structure that supports the axons as they pass through the eye wall. It is hypothesized that strains caused by intraocular pressure may initiate this damage and that these strains are modulated by the combined deformation of the LC and adjacent peripapillary sclera (PPS). In this study we present a method to measure the pressure-induced 3D displacement and strain field in the LC and PPS simultaneously. Regional strain variation in the LC and PPS was investigated and compared and strains were analyzed for associations with age, LC area, LC strain magnitude, and LC posterior motion relative to the PPS.
| S-EPMC8340454 | biostudies-literature
Project description:This study was designed to evaluate if primary open angle glaucoma (POAG) and its severity are associated with the shape of the lamina cribrosa (LC) as measured by a global shape index (LC-GSI), or other indices of LC curvature or depth. Optical coherence tomography (OCT) scans of the optic nerve head (OHN) were obtained from subjects with POAG (n?=?99) and non-glaucomatous controls (n?=?76). ONH structures were delineated, the anterior LC morphology reconstructed in 3D, and the LC-GSI calculated (more negative values denote greater posterior concavity). Anterior LC depth and 2D-curvature were also measured. Severity of glaucoma was defined by the extent of visual field loss, based on the Hodapp-Parrish-Anderson grading. Linear regression analyses compared LC characteristics between controls, mild-moderate, and advanced POAG groups. After adjusting for age, gender, ethnicity, intraocular pressure, axial length and corneal curvature, the LC-GSI was most negative in the advanced POAG group (mean [standard error]?=?-0.34 [0.05]), followed by the mild-moderate POAG group (-0.31 [0.02]) and then controls (-0.23 [0.02], PTrend?=?0.01). There was also a significant trend of increasing LC depth and greater LC horizontal curvature with increasing severity of glaucoma (PTrend?=?0.04 and 0.02, respectively). Therefore, with more severe glaucoma, the LC-GSI was increasingly more negative, and the anterior LC depth and curvature greater. These observations collectively correspond to greater cupping of the ONH at the level of the LC. As the LC-GSI describes the 3D anterior LC morphology, its potential usage may be complementary to existing ONH parameters measured on OCT.
| S-EPMC6488637 | biostudies-literature
Project description:PurposeTo investigate the relationship between corneal hysteresis (CH) and anterior lamina cribrosa surface (ALCS) displacement over time in a cohort of patients with glaucoma.DesignProspective observational case series.MethodsIn this study, 147 eyes from 96 glaucoma or glaucoma suspect patients were followed for a mean of 3.5 years and 7.9 visits. Baseline CH measurements were obtained using the Ocular Response Analyzer (ORA; Reichert Ophthalmic Instruments Inc, Depew, New York, USA). The mean anterior lamina cribrosa surface depth (ALCSD) and choroidal thickness were by automated segmentation of spectral-domain optical coherence tomography (SD-OCT) scans. The rate of change of ALCSD was calculated using linear mixed effects models. Relationship between baseline CH and follow-up ALCSD rate of change was adjusted for confounding factors, including age, intraocular pressure (IOP), and choroidal thickness.ResultsThe mean baseline CH was 9.4 mm Hg (95% confidence interval [CI] 9.1-9.7). Overall, the ALCS was displaced posteriorly at a rate of 0.78 μm/y (95% CI -1.82, 0.26). Seventeen eyes (11.5%) showed a significant posterior displacement of ALCS, whereas 22 eyes (15.0%) showed a significant anterior displacement of ALCS. The choroidal thickness thinned at a rate of -1.09 μm/y during the follow-up (P = .001). Multivariable mixed modeling showed that choroidal thinning, lower IOP change, and lower corneal hysteresis were significantly associated with posterior ALCS displacement over time (P = .034, P = .037, and P = .048). Each 1 mm lower CH was associated with 0.66 μm/y posterior displacement of the ALCS.ConclusionsLower corneal hysteresis was significantly associated with posterior displacement of the anterior lamina cribrosa over time. These data provide additional support for lower corneal hysteresis being a risk factor for glaucoma progression.
| S-EPMC7113091 | biostudies-literature
Project description:PurposeTo develop an ex vivo explant system using multiphoton microscopy and digital volume correlation to measure the full-field deformation response to intraocular pressure (IOP) change in the peripapillary sclera (PPS) and in the optic nerve head (ONH) astrocytic structure.MethodsGreen fluorescent protein (GFP)-glutamate transporter-GLT1 (GLT1/GFP) mouse eyes were explanted and imaged with a laser-scanning microscope under controlled inflation. Images were analyzed for regional strains and changes in astrocytic lamina and PPS shape. Astrocyte volume fraction in seven control GLT1/GFP mice was measured. The level of fluorescence of GFP fluorescent astrocytes was compared with glial fibrillary acidic protein (GFAP) labeled astrocytes using immunohistochemistry.ResultsThe ONH astrocytic structure remained stable during 3 hours in explants. Control strain-globally, in the central one-half or two-thirds of the astrocytic lamina-was significantly greater in the nasal-temporal direction than in the inferior-superior or anterior-posterior directions (each P≤ 0.03, mixed models). The PPS opening (perimeter) in normal eye explants also became wider nasal-temporally than superior-inferiorly during inflation from 10 to 30 mm Hg (P = 0.0005). After 1 to 3 days of chronic IOP elevation, PPS area was larger than in control eyes (P = 0.035), perimeter elongation was 37% less than controls, and global nasal-temporal strain was significantly less than controls (P = 0.007). Astrocyte orientation was altered by chronic IOP elevation, with processes redirected toward the longitudinal axis of the optic nerve.ConclusionsThe explant inflation test measures the strain response of the mouse ONH to applied IOP. Initial studies indicate regional differences in response to both acute and chronic IOP elevation within the ONH region.
| S-EPMC5295769 | biostudies-literature
Project description:PurposeTo investigate whether lamina cribrosa (LC) defects are associated with optic disc morphology in primary open angle glaucoma (POAG) eyes with high myopia.MethodsA total of 129 POAG patients and 55 age-matched control subjects with high myopia were evaluated. Three-dimensional scan images obtained by swept source optical coherence tomography were used to detect LC defects. Radial B-scans and infrared images obtained by spectral domain optical coherence tomography were used to measure ?-peripapillary atrophy (PPA) lengths with and without Bruch's membrane (BM) (temporal, nasal, superior, and inferior), tilt angle (vertical and horizontal), and disc diameter (transverse and longitudinal). Peripapillary intrachoroidal cavitations (PICCs), disc area, ovality index, and cyclotorsion of the optic disc were analyzed as well.ResultsLC defects were found in 70 of 129 (54.2%) POAG eyes and 1 of 55 (1.8%) control eyes (P < 0.001). Age, sex, spherical equivalent, axial length, intraocular pressure, and central corneal thickness were not significantly different among POAG eyes with LC defects, POAG eyes without LC defects, and control eyes. Temporal PPA lengths without BM in all three groups correlated significantly with vertical and horizontal tilt angles, although no PPA length with BM correlated significantly with any tilt angle. PICCs were detected more frequently in POAG eyes with LC defects than those without LC defects (P = 0.01) and control eyes (P = 0.02). POAG eyes with LC defects showed a smaller ovality index (P = 0.004), longer temporal PPA without BM (P < 0.001), and larger vertical/horizontal tilt angles (vertical, P < 0.001; horizontal, P = 0.01), and transverse diameter (P = 0.01). In multivariate analysis for the presence of LC defects, presence of POAG (P < 0.001) and vertical tilt angle (P < 0.001) were identified as significant.ConclusionsThe presence of LC defects was associated with myopic optic disc morphology in POAG eyes with high myopia.
| S-EPMC4274005 | biostudies-literature
Project description:To determine whether focal abnormalities of the lamina cribrosa (LC) are present in glaucomatous eyes with localized retinal nerve fiber layer (RNFL) defects.Cross-sectional, observational study.We analyzed 20 eyes of 14 subjects with localized RNFL defects detected by masked grading of stereophotographs and 40 eyes of 25 age-matched healthy subjects recruited from the Diagnostic Innovations in Glaucoma Study at the University of California, San Diego.All eyes had stereoscopic optic disc photography and in vivo LC imaging using enhanced depth imaging optical coherence tomography (EDI-OCT). Two masked graders identified focal LC defects defined by a standardized protocol using 48 radial scan EDI-OCT images. The kappa coefficient was calculated as a measure of the reliability of interobserver agreement.The number of focal LC defects and the relationship between the location of LC defects and the location of localized RNFL defects.Of 20 eyes with a localized RNFL defect, 15 (75%) had ?1 LC defect compared with only 1 of 40 healthy eyes (3%). There were 13 eyes with localized RNFL defects that had 1 LC defect, 1 eye with 2 LC defects, and 1eye with 3 LC defects. The largest area LC defect was present in a radial line EDI-OCT scan corresponding with a localized RNFL defect in 13 of 15 eyes (87%). There was good agreement between graders as to whether an eye had an LC defect (kappa = 0.87; 95% confidence interval [CI], 0.73-1.00; P<0.001) and the location of the largest defect (kappa = 0.72; 95% CI, 0.44-1.00; P<0.001).Focal defects of the LC were frequently visible in glaucomatous eyes with localized RNFL defects. Focal abnormalities of the LC may be associated with focal retinal nerve fiber damage.
| S-EPMC3947348 | biostudies-literature