Lamina cribrosa

Lamina cribrosa A series of perforated sheets of connective tissue that the optic nerve passes through as it exits the eye. 

Bellezza AJ, Rintalan CJ, Thompson HW, Downs JC, Hart RT, et al. 2003. Deformation of the lamina cribrosa and anterior scleral canal wall in early experimental glaucoma. Invest Ophthalmol Vis Sci 44 623-637. 

Increased elastin expression in astrocytes ofthe lamina cribrosa in response to elevated intraocular pressure. Invest Ophthalmol Vis Sci 42 2303-2314,... 

The sclera is composed of collagen fibrils embedded in a glycosaminoglycan (GAG) matrix. Scleral collagen is predominantly type I (7). Collagen types III, V, and VI, VIII, and XII are also found in human sclera (8-12), while the lamina cribrosa... 

Most cases of CRVO result from the formation of a thrombus at or just posterior to the lamina cribrosa (6). Systemic thrombolytic therapy was first attempted with anticoagulants in 1938. Costen et al. (41) described one case treated within seven hours of onset who had visual acuity improve from 20/200 to 20/30 over a period of 30 minutes due to presumed lysis of the thrombus, with venous filling time improving from 34.6 to 23.3 seconds on repeated fluorescein angiography. 

For both CRVO and BRVO the pathophysiology includes the formation of thrombosis within the venule, typically at the crossing point of an arteriole and venule in the case of BRVO, and at or just posterior to the lamina cribrosa in the case of CRVO. In both instances the compartment syndrome model has been proposed whereby the vein is partially compressed by the adjacent arteriole artery within a restricted space. This can lead to turbulence of blood flow, and secondary development of thrombosis. Surgical decompression of the vein or the surrounding structures has been proposed as a therapeutic procedure for both disorders. 

Hayreh (66) has argued that since the lamina cribrosa comprises a firm rather than elastic band of collagen tissue, an incision in one aspect should not relax the tissue and allow decompression of the central retinal vein. He has also commented that as the thrombosis is often posterior to the lamina cribrosa, decompression at... 

Figure 1 Schematic diagram of the eye in horizontal section indicating each ocular component, a, corneal epithelium b, keratocyte c, corneal endothelium d, aqueous humor e, conjunctiva /, sclera g, trabecular meshwork h, iris i, lens /, ciliary zonule and body k, vitreous /, retina m, interphotoreceptor matrix n, retinal pigment epithelium o, Bruch s membrane p, choroid q, optic nerve head r, lamina cribrosa extraocular muscles and tissues. The candidate glycosaminoglycans involved in the ocular components of each eye disease described in this chapter are as follows macular corneal dystrophy (b, c KS, CS/DS, HA), glaucoma (d HA g CS/DS, HS, HA q, r CS, HS, HA), cataract r. CS/DS, HS, HA), diabetic retinopathy (fc HA / HS), retinal detach-ment/proliferative vitreoretinopathy k, I, m, n CS/DS, HS, HA), myopia (f, p CS), thyroid eye disease (s CS, HA), pseudoexfoliation syndrome (c, d, g, h, i, j KS, CS/DS, HA). KS, keratan sulfate CS/DS, chondroitin sulfate/dermatan sulfate HS, heparan sulfate HA, hyaluronan.

Glaucoma is a type of optic neuropathy associated with characteristic optic disk damage, which may result in certain visual field loss patterns, at least partly in response to suboptimal intraocular pressure. There are three representative ocular lesions containing glycosaminoglycans, namely the aqueous humor, trabecular meshwork, and optic nerve head/lamina cribrosa, which are involved in glaucoma. 

The optic nerve head is the portion of the optic nerve observed in the fundus formed by the meeting of all the retinal nerve fibers. The lamina cribrosa is a thin sieve-like membrane composed of neuroglia and connective tissue that bridges the posterior scleral foramen and is continuous with the choroid and the deepest third of the sclera. Fiber bundles of the optic nerve pass through the perforations of the lamina cribrosa toward the optic chiasm. Because glycosaminoglycans and... 

The sulfated proteoglycans in the human lamina cribrosa showed age-related changes (32). In the eyes of older individuals, the chondroitin/dermatan sulfate and heparan sulfate proteoglycan filaments were found to be shorter than those in younger persons. A mild decline in the diameter of the filaments with aging was also noted. 

Sawaguchi S, Yue BY, Fukuchi T, Iwata K, Kaiya T. Sulfated proteoglycans in the human lamina cribrosa. Invest Ophthalmol Vis Sci 1992 33 2388-2398. 

Morrison J, Farrell S, Johnson E, Deppmeier L, Moore CG, Grossmann E. Structure and composition of the rodent lamina cribrosa. Exp Eye Res... 

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