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

Keratoconus is a bilateral disorder of corneal shape which may be sporadic or genetically determined. Early corneal thinning suggests that a functional loss of structural elements is a primary event in the disease. Tensile strength of the cornea is reduced and is expressed by signs of rupture and scarring in Bowman's layer, scarring in the substantia propria, and rupture of Descemet's membrane. The overall stretching of the cornea results in an increase in curvature while an increased area of the corneal surfaces probably determines the onset and form of Fleischer's ring and the occurrence of endothelial polymegathism. Biochemical studies have shown an increase in collagenolysis and of reduceable collagen cross-links, but there is inconsistent evidence of altered solubility or of hydroxyproline or proteoglycan content. Of recent interest is the characterization of proteoglycan bridges along and between corneal collagen fibrils in keratoconus and the apparent loss of keratan sulphate demonstrated by electron-histochemical and x-ray diffraction techniques. The manner in which this could interfere with corneal strength is discussed.
Cornea 1988
PMID:Keratoconus. 304 80

The posterior portion of the Descemet's membrane was studied by scanning and transmission electron microscopy; the materials comprised 87 human peripheral corneas with ages from 2 to 98 years, 5 monkey corneas and 4 rabbit corneas. In some specimens, the endothelium was removed by ultrasonication. After removal of the endothelium, "curly structures" were recognized on the surface of the Descemet's membrane, where the membrane showed a gradual thinning. These structures appeared along the whole circumference of the cornea with variable width in the human specimens, but in monkey and rabbit corneas, the extent of these structures was less than in the human cornea. The "curly structures" were not encountered in young subjects, and they increased with age. There was a positive correlation (r = 0.60, P less than 0.001) between the age and the extent of these structures. Other aging products of the Descemet's membrane, ie, Hassall-Henle bodies, were partly surrounded by the "curly structures". The human "curly structures" consisted of collagen fibrils, halo structures in the collagen bundles, wide-spacing fibers, microfibrils, ground substances containing minute filaments and a structure resembling the Descemet's membrane. Components of "curly structures" of the monkey and rabbit were almost the same as those of the human except for the Descemet's membrane-like structure.
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PMID:Electron microscopic observations of Descemet's membrane of peripheral cornea. 308 4

Increasing numbers of preserved corneas are being transplanted as the demand for optimal bioavailability for donor corneas increases. McCarey-Kaufman (MK) short-term storage provides a sufficient endothelial cell viability for a maximum of only 4 days. Organ culture of corneoscleral discs extends post mortem storage times up to 4 weeks. K-Sol, a new cornea storage medium with 2.5% chondroitin sulfate, containing no calf serum as source of foreign protein and no dextran as artificial dehydrating agent, permits tissue to be used for at least 2 weeks after enucleation stored at 4 degrees C. The corneal endothelium was intact, as demonstrated by subsequent vital staining and phase microscope evaluation. Pachymetric measurements showed regular thinning profiles in 31 K-Sol preserved corneas for corneal transplantation, with a clear outcome after a preliminary average observation time of six months.
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PMID:Recent advances in preservation of viable corneal tissue. 308 47

Explants of human corneas in organ culture were used to study the interaction between Neisseria gonorrhoeae and human corneal epithelium at an ultrastructural level. scanning electron microscopy revealed that infection of the corneal explants with N. gonorrhoeae resulted in a rapid adherence of the bacteria to the cell surface. This attachment was probably mediated by pili since only piliated strains were able to adhere to the cells. Upon attachment the bacteria appeared to become engulfed by the epithelial cells. Transmission electron microscopy revealed gonococci apparently lying within vacuoles inside the cells within 1 h after inoculation of the bacteria. At prolonged infection (8-24 h), the thickness of the epithelium was found to be considerably reduced. This thinning of the cornea was probably caused by a continuous desquamation of infected cells. Taken together, the present data demonstrate that Neisseria gonorrhoeae is able to adhere and penetrate into intact corneal epithelium and furthermore indicate that human cornea explants in organ culture are a useful model in studies of bacterial-epithelial cell interaction.
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PMID:The interaction between Neisseria gonorrhoeae and the human cornea in organ culture. An electron microscopic study. 313 97

Pellucid marginal corneal degeneration is a bilateral disease characterized by a narrow band of corneal thinning localized 1-2 mm from the inferior limbus. The disease is diagnosed usually between 20 and 50 years of life, and its etiology remains obscure. During the clinical course and evolution of pellucid marginal corneal degeneration, acute hydrops with corneal edema in the lower half may develop (acute pellucid marginal corneal degeneration). However, since cases of acute pellucid marginal corneal degeneration are not frequently encountered in clinical practice, each new patient is evaluated and managed with the utmost care to contribute to our better understanding of this disease. This is a report of two cases of acute pellucid marginal corneal degeneration that had a relatively favorable functional outcome when treated medically, so that corneal grafting was not necessary.
Cornea 1988
PMID:Acute pellucid marginal corneal degeneration. 321 64

Sixty-three cases of vascularised lipid keratopathy were treated with the argon laser to occlude feeder vessels which had been identified by fluorescein angiography. There was a reduction in extent in 62% and density in 49%. Visual acuity was improved in 48%. Six patients had keratoplasties shortly after treatment, none of which showed graft rejection. Minor complications included temporary haemorrhage into the cornea and iris atrophy. A more serious problem was severe corneal thinning after resorption of lipid. The patients had to be carefully followed up and maintained on a low dose of topical steroid.
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PMID:Argon laser treatment of lipid keratopathy. 322 45

We report two patients with keratoconjunctivitis sicca and rheumatoid arthritis whose corneal surfaces regained their integrity following tarsorrhaphy when conservative therapeutic measures were unsuccessful. We suggest that tarsorrhaphy be considered early in the course of the disease in such patients when other measures have failed to arrest progressive thinning of the cornea.
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PMID:Tarsorrhaphy for corneal disease in patients with rheumatoid arthritis. 334 Mar 99

Two similar cases of severe band keratopathy are reported that occurred about 4 weeks after routine intracapsular cataract extraction with implantation of an anterior chamber intraocular lens. The calcareous deposits were removed and analysed. The cornea remained damaged because of severe, irregular thinning. The cause of the condition could not be determined.
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PMID:[Severe band keratopathy following cataract surgery with intraocular lens implantation]. 342 40

In a study reported recently, the effects of long-term extended wear of soft contact lenses on the human cornea were found to include epithelial thinning, a reduction in epithelial oxygen uptake, induction of epithelial microcysts, stromal thinning, and an increase in endothelial polymegathism. A multiple regression analysis was performed on data from this study to identify lens or patient characteristics associated with these effects. Although generalization to the population of conclusions based on associations identified using a small sample should be treated with caution, results from this analysis suggest that lens-induced effects on the cornea may be minimized by fitting lenses that are thinner and more mobile, and by encouraging more frequent lens removal and replacement. Patients with thinner corneas and with high endothelial cell density and low polymegathism before commencing lens wear tended to show fewer effects from extended lens wear.
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PMID:Strategies for minimizing the ocular effects of extended contact lens wear--a statistical analysis. 347 6

Ophthalmological lesions enter in the definition of Cogan's syndrome, associated with vestibulo-auditory symptoms. They are present in almost one half of patients with Wegener's granulomatosis and in 10 to 20 p. 100 of patients with periarteritis nodosa, where they may be the initial symptom. Yet they are seldom described in leucocytoclastic angiitis of small vessels, 3 cases of which are reported here. The first case concerns a 71-year old woman with cutaneous leucocytoclastic angiitis which regressed within a few days under dapsone. However, the drug had to be withdrawn on account of acute haemolysis. Thereafter, new skin lesions and severe pain in the left eye with fall in visual acuity developed simultaneously. Eye examination showed a large, marginal ulceration of the cornea extending to the adjacent sclera and reflecting deep involvement of the sclerocorneal limbus. Systemic corticosteroid therapy in doses of 1 mg/kg/day was instituted, resulting in gradual disappearance of the skin lesions and stabilization of the ophthalmic lesion. There remains, however, thinning of the cornea and sclera which entails a definite risk of perforation should the angiitis recur. The second patient was a 54-year old man seen for fever, polyarthralgia, purpura of the lower limbs and rapidly extending necrotic ulceration of the scrotum. A few days previously, inflammatory chemosis of the right eye had suddenly developed. Under systemic corticosteroids (1.5 mg/kg/day), the ophthalmic symptoms rapidly regressed, but the patient died of digestive tract haemorrhage. The third case was that of a 36-year old woman with urticaria associated with arthralgias and diffuse myalgia.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Ophthalmologic manifestations of leukocytoclastic vasculitis. Apropos of 3 case reports]. 357 12


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