Massive suprachoroidal hemorrhage with retinal and vitreous incarceration; a vitreoretinal surgical approach.
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Suprachoroidal hemorrhage(SH) may cause the expulsion of the intraocular contents. Vitreous incarceration in the wound and retinal detachment with SH are extremely poor prognostic signs. Treatment modalities depend on the severity of eye damage. This particular patient had "kissing" hemorrhagic choroidal detachment which completely filled the vitreous cavity after cataract surgery. It seemed to be inoperable. Secondary surgery was delayed 3 days to lower IOP to normal levels. The eye underwent anterior drainage sclerotomy under constantly-maintained limbal or pars plana infusion fluid line pressure. The authors performed a pars plana vitrectomy, followed by perfluorocarbon liquid injection and a silicone oil tamponade. After this surgical approach, the patient attained an attached retina and a visual acuity of 5/200 at the 3 month follow-up. (+info)
The paretic pupil: its incidence and aetiology after keratoplasty for keratoconus.
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The present study reveals that pupillary abnormalities are common after keratoplasty for keratoconus and that, in addition to the fixed dilated pupils which we have found in 7.8 per cent. of eyes, varying degrees of partially dilated pupil frequently occur after operation. In our experience, glaucoma is not a sequel to the simple paretic pupil, a finding which confirms the results of the smaller series of Alberth and Schnitzler (1971); glaucoma thus seems to be no more a special complication of keratoplasty for keratoconus than it is of keratoplasty for any other corneal pathology. The paretic pupils can be explained on the basis of ischaemic atrophy of the sphincter pupillae muscle secondary to an iris strangulation phenomenon occurring during surgery in the manner we have discussed. The relative frequency of a dilated pupil, together with the common finding of focal iris atrophy after minimal surgical trauma to the iris in cases of keratoconus, forces one to conclude that the pathology in this condition is not confined to the cornea but probably extends to the iris and possibly to the scleral envelope as well. (+info)
Giant vacuoles are found preferentially near collector channels.
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PURPOSE: To determine whether giant vacuoles form preferentially near collector channels or over regions of optically empty space within the juxtacanalicular tissue (JCT). METHODS: To assess the relationship between giant vacuoles and collector channels, six eyes were perfused with phosphate-buffered saline (PBS) at 20 mm Hg and then fixed by perfusion. Serial sections were cut in the frontal plane and light microscopy used to count the number of giant vacuoles per length of Schlemm's canal. The number of giant vacuoles between two adjacent collector channels was determined. To assess the relationship between giant vacuoles and the ultrastructure of the JCT, an additional seven eyes were perfused with PBS at 10 mm Hg, fixed by perfusion, and examined by transmission electron microscopy. The ultrastructural components of the JCT were quantitated with an image analysis system. RESULTS: Twice as many giant vacuoles were present in regions underlying collector channels as in regions between channels (giant vacuoles per histologic section: 14.0 +/- 1.7 versus 7.3 +/- 0.8, P: = 0.01). Giant vacuoles occurred on both the inner and outer walls of the canal but were more numerous on the inner wall (9.1 +/- 1.0 versus 2.6 +/- 0.4, P: < 0.001). No significant increase in optically empty space was found in the JCT regions underlying giant vacuoles compared with regions with no vacuoles (50.7% +/- 2.3% versus 47.3% +/- 2.5%, P: = 0.09). Examination of the amount of optically empty space immediately adjacent (within 1 microm) to the inner wall endothelial cells of the canal did not reveal a significant difference between regions under vacuoles and regions without giant vacuoles. CONCLUSIONS: Giant vacuoles are found preferentially near collector channels, indicating that aqueous flow across the inner wall is sensitive to downstream pressure. The variability in giant vacuole distribution noted in previous studies is in part due to the distance of the vacuoles from the collector channels. No distinct findings in the JCT were associated with the presence of giant vacuoles. (+info)
The optic nerve head as a biomechanical structure: initial finite element modeling.
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PURPOSE: To study the relationship between intraocular pressure (IOP) and the IOP-related stress (force/cross-sectional area) it generates within the load-bearing connective tissues of the optic nerve head. METHODS: Thirteen digital, three-dimensional geometries were created representing the posterior scleral shell of 13 idealized human eyes. Each three-dimensional geometry was then discretized into a finite element model consisting of 900 constituent finite elements. In five models, the scleral canal was circular (diameters of 0.50, 1.50, 1.75, 2.00, and 2.56 mm), with scleral wall thickness (0.8 mm) and inner radius (12.0 mm) held constant. In three models, the canal was elliptical (vertical-to-horizontal ratios of 2:1 [2.50 x 1.25 mm], 1.5:1 [2.1 x 1.4 mm], and 1.15:1 [1.92 x 1.67 mm]), with the same constant scleral wall thickness and inner radius. In five additional models, scleral canal size was held constant (1.92 x 1.67 mm), and either scleral wall thickness (three models, 0.5, 1.0, and 1.5 mm) or inner radius (two models, 13.0 and 14.0 mm) was varied. In all models, each finite element was assigned a single isotropic material property, either scleral (modulus of elasticity, 5500 kPa) or axonal (modulus of elasticity, 55 kPa). Maximum stresses within specific regions were calculated at an IOP of 15 mm Hg (2000 Pa). RESULTS: Larger scleral canal diameter, elongation of the canal, and thinning of the sclera increased IOP-related stress for a given level of IOP. For all models, maximum IOP-related stress ranged from 6 x IOP (posterior sclera) to 122 x IOP (laminar trabeculae). For each model, maximum IOP-related stress was highest within the laminar trabecular region and decreased progressively through the laminar insertion, peripapillary scleral, and posterior scleral regions. Varying the inner radius had little effect on the maximum IOP-related stress within the scleral canal. CONCLUSIONS: Initial finite element models show that IOP-related stress within the load-bearing connective tissues of the optic nerve head is substantial even at low levels of IOP. Although the data suggest that scleral canal size and shape and scleral thickness are principal determinants of the magnitude of IOP-related stress within the optic nerve head, models that incorporate physiologic scleral canal and laminar geometries, a more refined finite element model meshwork, and nonisotropic material properties will be required to confirm these results. (+info)
Localization of MYOC transcripts in human eye and optic nerve by in situ hybridization.
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PURPOSE: To evaluate MYOC (myocilin) gene expression at the RNA level in normal intact human eyes and optic nerve using in situ hybridization. METHODS: Normal human eyes and optic nerves from donors 62 to 83 years of age with no history of glaucoma were fixed, embedded in paraffin, and sectioned. Sections were hybridized with (35)S-labeled sense and antisense riboprobes derived from a full-length MYOC cDNA. RESULTS: High levels of MYOC expression were observed throughout the trabecular meshwork as well as in the most anterior nonfiltering meshwork (Schwalbe's line), in the scleral spur, and in the endothelial lining of Schlemm's canal. MYOC transcripts were also detected in the anterior corneal stroma, in the ciliary muscle, beneath the anterior border of the iris, in the iris stroma, and in the sclera. Expression in the retrolaminar region of the optic nerve was present in the pial septa that divide the nerve fiber bundles, in the perivascular connective tissue surrounding the central retinal vessels, and in the dura mater, arachnoid, and pia mater of the meningeal sheath surrounding the optic nerve. CONCLUSIONS: MYOC gene expression in the trabecular meshwork, Schlemm's canal, scleral spur, and ciliary muscle indicates a structural or functional role for myocilin in the regulation of aqueous humor outflow that may influence intraocular pressure. MYOC expression in the optic nerve suggests that changes in the structural, metabolic, or neurotropic support of the optic nerve may influence its susceptibility to glaucomatous damage. (+info)
Scleral remodeling during the development of and recovery from axial myopia in the tree shrew.
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PURPOSE: Recent investigations have suggested that scleral thinning in mammalian eyes with axial myopia is a consequence of the loss of scleral tissue, rather than the redistribution of existing tissue as the eye enlarges. The present study investigated whether further changes in the distribution and metabolism of scleral tissue occur during the process of recovery from axial myopia. Scleral glycosaminoglycan (GAG) synthesis and content as well as scleral dry weight changes were monitored as indicators of remodeling in myopic and recovering tree shrew sclerae. METHODS: Myopia was induced in tree shrews by monocularly depriving them of pattern vision. Some animals then had the occluder removed and were allowed to recover from the induced myopia for periods of 1, 3, 5, 7, and 9 days. Newly synthesized GAGs were radiolabeled in vivo with [(35)S]sulfate. Sulfate incorporation and total GAG content in the sclera was measured through selective precipitation of GAGs from proteinase K digests with alcian blue dye. Dry weights of the sclerae were also determined. Changes in ocular refraction and eye size were monitored using retinoscopy, keratometry, and ultrasonography. RESULTS: Eyes developing myopia showed a significant reduction in scleral GAG synthesis, particularly in the region of the posterior pole (-36% +/- 7%) compared with contralateral control eyes. Scleral dry weight was also significantly reduced in these eyes (-3.7% +/- 1.2%). In recovering eyes, significant changes in GAG synthesis were apparent after 24 hours of recovery. After 3 days of recovery, significantly elevated levels of GAG synthesis were found (+79% +/- 15%), returning to contralateral control eye values after 9 days of recovery. Interocular differences in scleral dry weight were shown to follow a similar pattern to that observed for GAG synthesis. CONCLUSIONS: Active remodeling, resulting in either the loss or replacement of scleral tissue and not passive redistribution of scleral tissue, is associated with changes in eye size during both myopia development and recovery. Regulatory changes in scleral metabolism can be rapidly evoked by a change in visual conditions and the direction of regulation is related to the direction of change in eye size. (+info)
Mooren's ulcer. Treatment by conjunctival excision.
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Ten eyes with progressing Mooren's or similar ulcers were treated by excising a 3 to 4 mm ring of limbal conjunctiva adjacent to the ulcer. Eight eyes healed within 3 weeks. Seven of these eyes have remained healed, while one eye has had repeated ulcers which healed when re-treated with conjunctival exicision. (+info)
Enhanced short-term plasmid transfection of filtration surgery tissues.
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PURPOSE: To quantify and localize plasmid transfection of filtration surgery tissues using two delivery techniques. METHODS: Full-thickness filtering procedures were performed on eyes of New Zealand albino rabbits. In 10 eyes, naked plasmid DNA in saline was either injected beneath Tenon's capsule at the filtration site or absorbed into a collagen shield that was then placed external to the sclerostomy and under the Tenon's capsule. Forty-eight hours after surgery, levels of the reporter gene, chloramphenicol acetyltransferase (CAT) were measured in samples of ocular tissues. In two additional eyes, the ss-galactosidase (ss-GAL:) reporter gene expression was localized histologically. RESULTS: Injection of plasmid DNA in saline vehicle into the filtration bleb produced readily detectable CAT activity in bleb tissue (conjunctiva, Tenon's capsule, and sclera) whereas CAT activity was nearly undetectable in samples of the cornea, iris-ciliary body, and tissues located opposite the bleb site. Delivery of the plasmid DNA into the bleb through a collagen shield increased CAT activity 30-fold over injection of plasmid in saline (2711 +/- 567 mU/mg versus 92 +/- 38 mU/mg). ss-Gal activity was imaged only in the region of the bleb, and microscopic examination showed ss-Gal activity localized to Tenon's capsule fibroblasts, with minimal ss-Gal activity observed in inflammatory cells or scleral fibroblasts. CONCLUSIONS: Transfection of filtration tissues is enhanced by absorption of naked DNA into a collagen shield. Furthermore, transfection is localized to the fibroblasts and inflammatory cells of the filtration bleb site. Gene therapy using naked plasmid DNA and a simple collagen shield delivery vehicle may be useful for regulating wound healing after glaucoma surgery. (+info)