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Query: UMLS:C0851184 (thinning)
 11,252 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human cadaver eyes can be dehydrated by prolonged elevation of intraocular pressure (three to five hours) or by hyperosmotic Dextran over a 20- to 30-minute period. We divided four pairs of donor eyes into two groups (A and B) and dehydrated four corneas by each method. After corneal thinning to 500 to 600 microns, central corneal pachymetry was measured every ten minutes during the rehydration period for one hour, with each cornea pair being moistened at a different rate (every 30 seconds, 1 minute, 2.5 minutes or 5 minutes). The resultant increase in central corneal thickness noted by change in pachymetry (delta P) ranged from 12.4% to 14.7% over one hour between the two groups. delta P did not differ significantly between groups A and B, regardless of the varying rate of balanced salt solution irrigation of the corneas. Thus, it appears that either method of corneal dehydration provides comparable stability of corneal thinning for at least one hour to allow consistent corneal dynamics for experimental refractive surgery.
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PMID:Human cadaver corneal thinning for experimental refractive surgery. 248 49

Periods of preservation for donor corneas, even for short times, are necessary to facilitate optimum conditions in penetrating keratoplasty. However, current techniques for corneal storage at low temperatures may not provide optimal conditions for maintaining tissue integrity. In particular, the ionic composition of the storage medium has received little attention since it has been assumed throughout that the normal complement of ions in tissue culture media will also be suitable for preservation at reduced temperatures. This study extends our previous investigations on the merits of using CPTES (corneal-potassium-TES), a potassium-rich balanced salt solution containing an impermeant anionic pH buffer (TES), as a storage solution specifically designed to prevent the loss of intracellular potassium and minimise endothelial cell swelling during the time that the normal regulatory processes are switched off. The effect of adding the natural polymer chondroitin sulphate (CS) as a colloid osmotic agent to the hyperkalaemic storage medium is now examined. Corneas stored in CPTES containing 2.5% chondroitin sulphate retained a very high level of structural and functional integrity after three, five, and seven days storage at 0 degrees C; furthermore, stromal swelling was restricted to only 21%. All corneas stored in CPTES + 2.5% CS showed active endothelial function by thinning efficiently at rates that were greater than those previously reported for rabbit corneas stored for similar lengths of time in either M-K medium or K-sol. The zwitterionic buffers TES and HEPES were interchangeable in the hyperkalaemic solution and were non-toxic to corneal endothelium at a concentration of 100 mM. These compounds offer excellent pH buffering in bicarbonate-free medium.
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PMID:Hypothermic preservation of corneas in a hyperkalaemic solution (CPTES): II. Extended storage in the presence of chondroitin sulphate. 251 Aug 16

Human saphenous veins were studied to determine alterations resulting from preparation by moist gauze wrapping, balanced salt solution immersion, and heparinized whole blood storage at 4 degrees C. Morphologic derangements of endothelial cells, smooth muscle cells, and adventitial tissues were pronounced in the nonblood preparations. In a second study, 20 canine jugular vein segments were interposed into the iliofemoral arterial circulation, with half the grafts prepared in balanced salt solution and half in whole blood. Veins were harvested monthly for 10 months, being subjected to light and electron microscopic examinations. No thromboses or stenoses occurred. Diffuse graft dilatation affected veins three times more often when stored in lactated Ringer's solution than when stored in heparinized blood. Medial thinning, ranging from 20% to 54%, occurred in veins stored in the balanced salt solution. Endothelial regeneration was complete in all grafts within 30 days after implantation. However, medial and adventitial injury to veins prepared in balanced salt solution appeared progressive, with fibrodysplastic tissue replacing smooth muscle cells. Plasmacytosis and neutrophil infiltrates, consistent with chronic active inflammation, often accompanied fibroproliferative changes. Alterations in medial structures, rather than endothelial injury, may have an important influence on the long-term durability of transplanted vein grafts.
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PMID:Ultrastructure of human and transplanted canine veins: effects of different preparation media. 684 85

Rabbit corneas were perfused in vitro with an irrigation solution for 90 minutes. This was followed by 6 hours of perfusion with tissue culture medium TC199 during which endothelial function was assessed by monitoring rates of swelling during a period of perfusion in the absence of bicarbonate ions, and subsequent rates of thinning when bicarbonate ions were restored to the perfusate. Corneal thickness (measured with an ultrasonic pachymeter) immediately following excision was 401 microns (SD 19, n = 23). During the 90 minute perfusion at 35 degrees C, corneas exposed to balanced salt solution (BSS), Hartmann's solution or 0.9% NaCl (all initially at room temperature) swelled, respectively, at 14 (SD 2.3, n = 4), 11 (SD 2.6, n = 4), and 70 (SD 4.3, n = 4) microns/h. Cold Hartmann's solution (initially at 4 degrees C) caused corneas to swell at 9 (SD 2.3, n = 4) microns/h. On the other hand, corneas perfused with BSS Plus thinned at 9 (SD 3.4, n = 4) microns/h and TC199 with Earle's salts had little effect on thickness. Rates of swelling and thinning during the following assessment perfusion showed no apparent effects of prior exposure to any of the irrigation solutions on the barrier properties or pump function of the endothelium. Despite this, the increased thickness of corneas exposed initially to BSS, cold Hartmann's solution, or 0.9% NaCl was not fully reversed, even by the end of the 6 hour assessment perfusion. In contrast, the swelling observed in corneas exposed to Hartmann's solution at room temperature was reversed and these corneas had returned to their normal thickness by the end of the assessment period. All corneas, even those exposed to 0.9% NaCl, had an intact endothelial mosaic with no evidence of damage or cell loss, although morphological differences in cell shape and the appearance of cell borders were evident compared with freshly isolated cornea.
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PMID:Effects of irrigation solutions on corneal endothelial function. 761 71

A 33-year-old woman had progressive blurred vision 2 weeks after uneventful laser in situ keratomileusis surgery. Initial satisfactory uncorrected visual acuity (UCVA) was complicated by postoperative dry eye and drug toxicity. Slitlamp biomicroscopy revealed diffuse punctate epithelial keratitis and inferior corneal epithelial defect with rolled-up epithelium on the flaps and the inferior unoperated cornea in both eyes. Diffuse inflammatory cell infiltrates were evident in the stroma. Stromal thinning was evident on serial Orbscan (Bausch & Lomb) and pachymetry examinations, and a hyperopic shift of almost +6 diopters was observed in the refractive error in both eyes. These examinations showed a gradual recovery of stromal thickness after copious hydration with balanced salt solution. The UCVA was 1.0 in both eyes after corneal rehydration.
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PMID:Toxic keratopathy-related corneal dehydration after laser in situ keratomileusis. 1612 7

Posterior lenticonus is a rare progressive disease characterized by protrusion of posterior lens capsule along with lens cortex into the vitreous cavity. It may be associated with local thinning or absence of posterior lens capsule. It generally occurs sporadically, but familial cases have also been reported. If visually significant or if amblyopia is present, lens removal is indicated. Treatment consists of clear or cataractous lens extraction, optical correction along with prompt amblyopia therapy. In this case, we propose a "jellyfish sign" seen intraoperatively, which is referred to the characteristic movement of the posterior capsular cataractous material on injection of balanced salt solution in the capsular bag.
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PMID:Jellyfish sign for intraoperative identification of posterior lenticonus. 2779 16