Displacement of Optic Nerve Head in Response to Short-term Intraocular Pressure Elevation in Human Eyes

Levy, Norman S.; Crapps, Elaine E.

doi:10.1001/archopht.1984.01040030630037

Cited by 139 publications

(96 citation statements)

References 10 publications

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“…[16][17][18][19][20][21][22] Pressure induced displacement of the optic nerve head in human cadaver eyes has been monitored by scanning laser tomography, 23 Doppler velocimetry, 24 and radiographic evaluation of platinum wires placed in the lamina cribrosa. 25 In contrast with these in vitro methods, 23 24 the technique described in this study identifies the three dimensional parameters of the pressure induced deformation at the level of the human lamina cribrosa, and uses this information to determine the biomechanical properties of the tissue as a function of age.…”

Section: Discussionmentioning

confidence: 43%

Age-related compliance of the lamina cribrosa in human eyes

Albon¹,

Purslow²,

Karwatowski³

1994

Journal of Biomechanics

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Aims-To investigate changes in the mechanical compliance of ex vivo human lamina cribrosa with age. Methods-A laser scanning confocal microscope was used to image the surface of the fluorescently labelled lamina cribrosa in cadaver eyes. A method was developed to determine changes in the volume and strain of the lamina cribrosa created by increases in pressure. The ability of the lamina cribrosa to reverse its deformation on removal of pressure was also measured. Results-Volume and strain measurements both demonstrated that the lamina cribrosa increased in stiVness with age and the level of pressure applied. The ability of the lamina cribrosa to regain its original shape and size on removal of pressure appeared to decrease with age, demonstrating an age related decrease in resilience of the lamina cribrosa. Conclusions-The mechanical compliance of the human lamina cribrosa decreased with age. Misalignment of compliant cribriform plates in a young eye may exert a lesser stress on nerve axons, than that exerted by the rigid plates of an elderly lamina cribrosa. The resilience of the lamina cribrosa also decreased with age, suggesting an increased susceptibility to plastic flow and permanent deformation. Such changes may be of importance in the explanation of age related optic neuropathy in primary open angle glaucoma. (Br J Ophthalmol 2000;84:318-323) The lamina cribrosa is a lattice-like structure, consisting of successive perforated cribriform plates across the optic nerve canal, through which pass bundles of nerve fibres. The plates are lined by basement membranes and their cores are filled with significant amounts of fibrillar collagens and elastic fibres. During ageing, the constituents of these cribriform plates are altered. [1][2][3][4] It is likely that such changes will alter the mechanical behaviour of the ageing lamina cribrosa and therefore compromise its ability to support the nerve axons that pass through it.The distribution of axonal loss in early glaucoma appears to be related to regional diVerences in architecture of the lamina cribrosa. The superior and inferior regions of the lamina cribrosa, which exhibit greater pore size and less dense connective tissue, are thought to be more susceptible to axonal damage.5 6 The arcuate retinal ganglion cell axons, which pass through these regions, are damaged first in early glaucoma.The cause of glaucomatous axonal damage is unknown; ischaemia and mechanical damage as a result of a raised intraocular pressure or rearrangement of the cribriform plates are among the theories that have been proposed. [7][8][9] Whatever the cause, compression of the lamina cribrosa appears to occur before detectable glaucomatous field loss. 10Age related changes in the lamina cribrosa include increases in the amounts of collagen types I, III, and IV 3 4 within the cribriform plates, which lead to an overall increase in total collagen content. [1][2][3] We have also demonstrated alterations in the ratio of collagen types I and III and an increase in non-enzymatic glyc...

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Section: Discussionmentioning

confidence: 43%

Age-related compliance of the lamina cribrosa in human eyes

Albon¹,

Purslow²,

Karwatowski³

1994

Journal of Biomechanics

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“…This may induce changes in load-bearing connective tissues that results in laminar thinning, peripapillary scleral bowing posteriorly, and expansion of the scleral canal. 4,[25][26][27][28][29][30] Our findings in humans are consistent with experimental studies in dogs. Using confocal scanning laser tomography, 31,32 has shown that intracranial hypertension displaces the optic disc surface and lamina cribosa anteriorly (toward the vitreous), whereas ocular hypertension displaces the disc surface posteriorly.…”

Section: Discussionmentioning

confidence: 48%

Optical Coherence Tomography of the Swollen Optic Nerve Head: Deformation of the Peripapillary Retinal Pigment Epithelium Layer in Papilledema

Kupersmith

Sibony

Mandel

et al. 2011

Invest. Ophthalmol. Vis. Sci.

129

100

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PURPOSE.To examine the biomechanical deformation of load bearing structures of the optic nerve head (ONH) resulting from raised intracranial pressure, using high definition optical coherence tomography (HD-OCT). The authors postulate that elevated intracranial pressure induces forces in the retrolaminar subarachnoid space that can deform ONH structures, particularly the peripapillary Bruch's membrane (BM) and RPE layers. METHODS.The authors compared HD-OCT optic nerve and peripapillary retinal nerve fiber layer (RNFL) findings in eyes with papilledema caused by raised intracranial pressure to findings in eyes with optic disc swelling caused by optic neuritis and nonarteritic anterior ischemic optic neuropathy (NAION), conditions without intracranial hypertension. The authors measured average thickness of the RNFL and the angle of the RPE/BM at the temporal and nasal borders of the neural canal opening. The angle was measured as positive with inward (toward the vitreous) angulation and as negative with outward angulation. RESULTS. Of 30 eyes with papilledema, 20 eyes (67%) had positive RPE/BM rim angles. One of eight optic neuritis (12%) eyes and 1 of 12 NAION (8%) eyes had positive angulation. In five eyes with papilledema, RNFL thickening increased, three of which developed positive RPE/BM angles. On follow-up, 22 papilledema eyes had a reduction of RNFL swelling, and 17 of these eyes had less positive RPE/BM angulation. CONCLUSIONS. In papilledema, the RPE/BM is commonly deflected inward, in contrast to eyes with NAION or optic neuritis. The RPE/BM angulation is presumed to be caused by elevated pressure in the subarachnoid space, does not correlate with the amount of RNFL swelling, and resolves as papilledema subsides. (Invest Ophthalmol Vis Sci. 2011;52: 6558 -6564) DOI:10.1167/iovs.10-6782 P apilledema is caused by increased intracranial pressure. Histopathologic studies in animal models have shown that elevated pressure within the optic nerve sheath causes stasis of axoplasmic flow and decreased blood flow to axons in the neural canal.1-3 The ensuing optic disc swelling (papilledema) is a consequence of axonal distension of the prelaminar and peripapillary nerve fibers. Vascular congestion, leakage, and ischemia follow the acute axoplasmic flow stasis and are associated with interstitial edema. Although the proximate cause of early edema is stagnant axonal transport, there still remains some uncertainty about the relative effects of compression and ischemia. 1-3Burgoyne et al. 4 and others 5-11 have proposed a conceptual approach that analyzes the optic nerve head (ONH) as a biomechanical structure. They hypothesize that stress (force/ cross-sectional area) and strain (local deformation) on the ONH may be key determinants of axonal, glial, and vascular dysfunction in the pathogenesis and progression of glaucoma. Although the forces acting on the nerve head in papilledema differ from those in glaucoma, the application of biomechanical principles may provide insights about the clinical effects of intracrania...

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“…They postulated that when IOP was reduced after glaucoma filtering surgery, anterior repositioning of posteriorly displaced lamina cribrosa and simultaneous reformation of neuroretinal tissue would occur. 19,20 Cup shape is a description of the distribution of depth values. Cups with gradually sloping borders tend to have more negative values, and cups with steep sloping walls tend to have less negative or even positive values.…”

Section: Short-term Changes After Trabeculectomy M Figus Et Almentioning

confidence: 47%

Short-term changes in the optic nerve head and visual field after trabeculectomy

Figus

Lazzeri

Nardi

et al. 2011

Eye

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Aims or Purpose To evaluate short-term changes in optic nerve head topography and visual field induced by surgical reduction of intraocular pressure. Methods A prospective study was performed on 56 eyes of 56 patients with uncontrolled primary open-angle glaucoma despite maximum medical therapy, which underwent trabeculectomy. Optic nerve head evaluations by means of Heidelberg Retina Tomograph, and visual field tests were performed pre-operatively, and at 3 and 6 months after surgery. Differences in intraocular pressure, visual field indices, and Heidelberg Retina Tomograph parameters were evaluated with the t-test for paired data. A linear regression model was calculated to analyze the relationship between intraocular pressure reduction and visual field changes, and optic nerve head changes. Results Mean intraocular pressure decreased from 24.4 ± 5.0 mm Hg to 12.1 ± 3.1 mm Hg (month 3, Po0.001), and 10.6±2.8 mm Hg (month 6, Po0.001) after trabeculectomy. Mean retinal nerve fiber layer thickness (baseline, 0.19±0.034; month 3, 0.24 ± 0.039, P ¼ 0.05; month 6, 0.21 ± 0.037, P ¼ 0.05) showed a statistical significant change compared with baseline values. Conclusions In this 6-months study, a significant increase in retinal nerve fiber layer thickness was detected after glaucoma filtration surgery.

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Displacement of Optic Nerve Head in Response to Short-term Intraocular Pressure Elevation in Human Eyes

Cited by 139 publications

References 10 publications

Age-related compliance of the lamina cribrosa in human eyes

Age-related compliance of the lamina cribrosa in human eyes

Optical Coherence Tomography of the Swollen Optic Nerve Head: Deformation of the Peripapillary Retinal Pigment Epithelium Layer in Papilledema

Short-term changes in the optic nerve head and visual field after trabeculectomy

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