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

Pellucid marginal degeneration of the cornea is a bilateral, clear, inferior, peripheral corneal-thinning disorder. Protrusion of the cornea occurs above a band of thinning, which is located 1 to 2 mm from the limbus and measures 1 to 2 mm in width. American ophthalmologists are generally not familiar with the condition because most of the literature concerning pellucid degeneration is European. Four cases are described. This condition is differentiated from other noninflammatory cornel-thinning disorders such as keratoconus, keratoglobus, keratotorus, and posterior keratoconus. It is also differentiated from peripheral corneal disorders associated with inflammation such as Terrien's peripheral corneal degeneration, Mooren's ulcers, and ulcers from connective tissue disease.
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PMID:Pellucid marginal corneal degeneration. 35 10

The type of corneal ectasia, the presence of breaks in Descemet's membrane, and the success with contact lens wear or penetrating keratoplasty were studied in 61 patients with corneal ectasia and vernal keratoconjunctivitis. There were 53 patients with keratoconus, 5 with pellucid marginal corneal degeneration, 2 with keratoglobus, and 1 with superior corneal thinning. The high rate of hydrops and the corneal ectasia itself may be related to excessive eye rubbing. Success with contact lens wear or penetrating keratoplasty in vernal keratoconjunctivitis patients with keratoconus is less than in patients with keratoconus alone.
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PMID:Corneal ectasia in vernal keratoconjunctivitis. 261 47

Keratoglobus is a bilateral corneal disease characterised by thinning and protrusion of the entire corneal surface. The cornea is of normal size and usually transparent. Acute corneal edema due to rupture of Descemet's membrane and perforation even from minimal trauma are the most frequent complications. Keratoglobus may be associated with blue sclera, hyperextensibility of the joints or auditory problems. Most often it is a congenital disease with autosomal recessive transmission, but it may be secondarily acquired to an advanced keratopathy (keratoconus), to trauma or to exophthalmos. We report 5 cases of keratoglobus. 4 patients underwent penetrating keratoplasty. The anatomical abnormalities of congenital keratoglobus (3 cases) are constants : an absent Bowman's membrane, a disorganized stroma containing granular material, a thickened, striated Descemet's membrane with breaks, folds and verrucosities. On the other hand, acquired keratoglobus (1 case) shows localised breaks in Bowman's membrane resembling those of keratoconus. The anatomopathological differences are discussed.
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PMID:[Keratoglobus]. 388 24

Keratoconus and other noninflammatory corneal thinning disorders (keratoglobus, pellucid marginal degeneration and posterior keratoconus) are characterized by progressive corneal thinning, protrusion and scarring; the result is distorted and decreased vision. The etiology and pathogenesis of these disorders are unknown but may be associated with a variety of factors, including contact lens wear, eye rubbing, Down's syndrome, atopic disease, connective tissue disease, tapetoretinal degeneration and inheritance. Recent advances in techniques for biochemical and pathological investigation are now allowing further exploration in these areas. Early diagnosis is aided by the finding of irregular corneal astigmatism with inferior corneal steepening. Treatment ranges from simple spectacle correction to keratoplasty. In this review, the past and present literature on corneal thinning disorders is reviewed and practical approaches to diagnosis and management are outlined.
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PMID:Keratoconus and related noninflammatory corneal thinning disorders. 623 Jul 45

The authors examined four cases of keratoglobus and report here on the histological changes found: degenerative alterations of the epithelium, characteristic changes of Bowman's membrane, such as thinning, detachment and wrinkling, alterations of the stroma and secondary alterations of the Descemet's membrane. These results indicate that keratoglobus is nearly an extreme variant of keratoconus.
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PMID:[Histology of keratoglobus (author's transl)]. 745 38

Eleven patients with blue sclera, limbus-to-limbus corneal thinning, hypermobile joints, and consanguineous parents were examined between January 1983 and September 1991. The clinical diagnosis was consistent with the Ehlers-Danlos syndrome type VI phenotype in all patients. A "halo" sign at the limbus was present in all patients. Corneal rupture occurred in seven patients (nine eyes) either spontaneously or following minimal trauma. Acute hydrops occurred in three patients. Bilateral microcornea was present in one patient and two patients had a unilateral increased corneal diameter as a result of secondary glaucoma after trauma. Peripheral sclerocornea was present bilaterally in five patients. Curvature abnormalities included cornea plana, keratoconus, and keratoglobus.
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PMID:Corneal abnormalities in Ehlers-Danlos syndrome type VI. 845 32

Pellucid marginal corneal degeneration (PMCD) is an uncommon cause of inferior peripheral corneal ectasia, affecting patients between the ages of 20 and 40 years. Although histopathologically it is considered a variant of keratoconus, it differs in that the marked corneal steepening occurs more inferiorly, above a narrow band of corneal stromal thinning concentric to the inferior limbus. Here we present two cases. The first case is a clinically typical bilateral PMCD with a characteristic pattern of irregular against-the-rule astigmatism on corneal topography. The second case had an uncommon presentation of hydrops in a clinically keratoglobic eye which showed a marked steepening of the inferior corneal periphery on corneal topography. The other eye showed both clinically and topographically the features of PMCD. Corneal topography suggested that in the second patient, PMCD may have preceded the development of keratoglobus. Keratoconus, PMCD and keratoglobus are considered to be associated as part of the spectrum of non-inflammatory corneal thinning disorders. However, although the finding of PMCD and keratoconus in fellow eyes has been reported, to the best of our knowledge progression from PMCD to keratoglobus has not previously been shown.
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PMID:Topographic analysis in pellucid marginal corneal degeneration and keratoglobus. 894 96

Keratoconus is a bilateral noninflammatory corneal ectasia with an incidence of approximately 1 per 2,000 in the general population. It has well-described clinical signs, but early forms of the disease may go undetected unless the anterior corneal topography is studied. Early disease is now best detected with videokeratography. Classic histopathologic features include stromal thinning, iron deposition in the epithelial basement membrane, and breaks in Bowman's layer. Keratoconus is most commonly an isolated disorder, although several reports describe an association with Down syndrome, Leber's congenital amaurosis, and mitral valve prolapse. The differential diagnosis of keratoconus includes keratoglobus, pellucid marginal degeneration and Terrien's marginal degeneration. Contact lenses are the most common treatment modality. When contact lenses fail, corneal transplant is the best and most successful surgical option. Despite intensive clinical and laboratory investigation, the etiology of keratoconus remains unclear. Clinical studies provide strong indications of a major role for genes in its etiology. Videokeratography is playing an increasing role in defining the genetics of keratoconus, since early forms of the disease can be more accurately detected and potentially quantified in a reproducible manner. Laboratory studies suggest a role for degradative enzymes and proteinase inhibitors and a possible role for the interleukin-1 system in its pathogenesis, but these roles need to be more clearly defined. Genes suggested by these studies, as well as collagen genes and their regulatory products, could potentially be used as candidate genes to study patients with familial keratoconus. Such studies may provide the clues needed to enable us to better understand the underlying mechanisms that cause the corneal thinning in this disorder.
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PMID:Keratoconus. 949 73

We report sporadic, bilateral keratoglobus associated with posterior subcapsular cataract in a 43-year-old man. Slitlamp biomicroscopy showed symmetric arcus senilis-like deposits, a polygonal appearance resembling crocodile shagreen, an unusual endothelial appearance, and posterior subcapsular cataract. Orbscan II pachymetry maps (Bausch & Lomb) demonstrated bilateral diffuse corneal thinning (359.53 microm +/- 21.15 [SD] in the right eye and 379.61 +/- 11.49 microm in the left eye). These thickness values were confirmed by ultrasound pachymetry. In vivo confocal microscopy showed multiple criss-crossing dark lines and no identifiable cellular elements within the stroma. There were mild to moderate, guttata-like endothelial changes surrounded by pleomorphic cells. Phacoemulsification was performed in the left eye after careful consideration of the presenting features and modification of the surgical technique. Minimal structural alteration was observed during microstructural analysis 7 months after surgery. The endothelial morphology postoperatively was similar to that at baseline.
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PMID:Keratoglobus and posterior subcapsular cataract: surgical considerations and in vivo microstructural analysis. 1496 95

Keratoglobus is a rare bilateral condition characterized by a globular protrusion of the cornea. The cornea remains transparent and shows a generalized thinning, most pronounced in the periphery. Most often keratoglobus is a congenital disease, but it may be secondarily acquired. This corneal pathology causes severe visual impairment: it induces extreme myopia, irregular astigmatism, and corneal scarring due to previous hydrops. Spectacle corrections are utilized as long as they provide adequate visual function. Surgery is performed when visual needs are no longer satisfied. However, surgical management of this disease is difficult because of the extreme thinness of the entire cornea. Penetrating keratoplasty is one of the first surgical approaches to have been tested, but it has been partly renounced in favor of more complex procedures. Optimal surgical treatment for keratoglobus remains unknown because of the scarcity of reported surgical results.
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PMID:[Keratoglobus: review of the literature]. 1639 11


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