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Corneal Transplants (corneal + transplant)

Distribution by Scientific Domains
Medical Sciences100%

Selected Abstracts

Corneal transplant with topical tetracaine 1% as the sole anaesthetic agent

ACTA OPHTHALMOLOGICA, Issue 2 2009
Shahram Kashani
[source]

Corneal Graft Rejection Is Accompanied by Apoptosis of the Endothelium and Is Prevented by Gene Therapy With Bcl-xL

AMERICAN JOURNAL OF TRANSPLANTATION, Issue 9 2007
R. N Barcia
Corneal transplants normally enjoy a high percentage of survival, mainly because the eye is an immune-privileged site. When allograft failure occurs, it is most commonly due to rejection, an immune-mediated reaction that targets the corneal endothelium. While the exact mechanism by which the endothelium is targeted is still unknown, we postulate that corneal endothelial cell loss during allograft failure is mediated by apoptosis. Furthermore, because corneal endothelial cells do not normally regenerate, we hypothesize that suppressing apoptosis in the graft endothelium will promote transplant survival. In a murine model of transplantation, TUNEL staining and confocal microscopy showed apoptosis of the graft endothelium occurring in rejecting corneas as early as 2 weeks posttransplantation. We found that bcl-xL protected cultured corneal endothelial cells from apoptosis and that lentiviral delivery of bcl-xL to the corneal endothelium of donor corneas significantly improved the survival of allografts. These studies suggest a novel approach to improve corneal allograft survival by preventing apoptosis of the endothelium. [source]

The Influence of Rejection Episodes in Recipients of Bilateral Corneal Grafts

AMERICAN JOURNAL OF TRANSPLANTATION, Issue 4 2010
K. A. Williams
We investigated whether a rejection episode in one graft was associated with rejection in the other graft, in recipients with bilateral corneal transplants. In a prospectively maintained, national register of 14 865 followed corneal grafts, 1476 patients with bilateral penetrating corneal grafts were identified. Occurrence of rejection was a risk factor for graft failure (p < 0.0001). Logistic regression was used to calculate the adjusted odds ratio for rejection in one eye following rejection in the other eye. In the subset of 1118 patients with bilateral grafts but no history of previous grafts or rejections in either eye, the adjusted odds ratio for a rejection episode in the first eye following rejection in the second was 3.27 (95% confidence interval, CI 1.85, 5.79; p < 0.001). The adjusted odds ratio was 2.04 (95% CI 1.07, 3.91; p = 0.03) for rejection in the second eye following rejection in the first. The median time between the first rejection episode in one eye and the first rejection episode in the other eye was 15 months. Patients with bilateral corneal grafts who suffer a graft rejection episode in one eye are at significantly greater odds of suffering a rejection episode in the other corneal transplant. [source]

3236: Corneal grafting assisted by wavelength-optimised ultrashort pulser lasers

ACTA OPHTHALMOLOGICA, Issue 2010
TAL MARCIANO
Purpose We realized an innovative device for ocular surgery by ultrafast pulse laser optimised for corneal grafting. Methods We constructed a demonstrator device that reproduces surgical conditions of corneal transplant. It is thus possible to realize with the help of an easy handling automatised interface all the kinds of already existing corneal transplants. Also, in order to maximize the spatial quality of the beam, a wavefront correction system using a deformable mirror module has been added. The Demonstrator contains an erbium fiber laser emitting at 1,6 microns. This laser delivers a beam of a few Joule with pulse duration of 700 femtoseconds and a repetition rate of 100-200 KHz. It includes deformable mirrors permitting horizontal displacements and a wavefront sensor. It also contains the administration system of the laser beam. Results The experiments carried out with a surgical tunable source confirmed the initial assumptions: the penetration depth is limited to wavelengths close to 1 microns. When increasing the wavelength, the drop of the scattering compensates the absorption and therefore the penetration depth is slowly varying when increasing the wavelength. The laser does not penetrate near the maximum of the water absorption band located at 1,45 microns. However, the use of a wavelength of 1,6 micros enables an important increasing of penetration depth (factor 3) while conserving the same energy of current technologies. Conclusion The use of a laser source with a wavelength corresponding to the window of transparency of the cornea (1,65 microns) permits to increase both the penetration depth of an ultrafast laser source and the cut quality. [source]

Effect of voriconazole on a corneal abscess caused by fusarium

ACTA OPHTHALMOLOGICA, Issue 6 2004
Anna Polizzi
Abstract. Purpose:, To describe a case of corneal abscess caused by Fusarium solani that did not respond to common antifungal agents. Method:, Case report. Results:, Twenty days after accidental contact with vegetation, a 56-year-old man presented with a corneal abscess. Corneal ulceration developed and a perforating keratoplasty was performed. After a microbiological examination, the diagnosis of F. solani infection was made. Systemic and topical amphotericin B and fluconazole were prescribed, with no results. A new abscess formed on the transplanted graft and a wound leak developed. We administered topical and systemic voriconazole. No side-effects were observed. The choroidal detachment and the surgical transplant recovered completely in 20 days. A vascular leukoma developed at the site of the transplanted corneal abscess. Conclusion:, From a functional point of view, another corneal transplant will be necessary. Voriconazole was effective in treating a severe keratomycosis caused by F. solani that was resistant to other topical and systemic antifungal agents. [source]

Myiasis as a risk factor for prion diseases in humans

JOURNAL OF THE EUROPEAN ACADEMY OF DERMATOLOGY & VENEREOLOGY, Issue 9 2006
O Lupi
Abstract Prion diseases are transmissible spongiform encephalopathies of humans and animals. The oral route is clearly associated with some prion diseases, according to the dissemination of bovine spongiform encephalopathy (BSE or mad cow disease) in cattle and kuru in humans. However, other prion diseases such as scrapie (in sheep) and chronic wasting disease (CWD) (in cervids) cannot be explained in this way and are probably more associated with a pattern of horizontal transmission in both domestic and wild animals. The skin and mucous membranes are a potential target for prion infections because keratinocytes and lymphocytes are susceptible to the abnormal infective isoform of the prion protein. Iatrogenic transmission of Creutzfeldt,Jakob disease (CJD) was also recognized after corneal transplants in humans and scrapie was successfully transmitted to mice after ocular instillation of infected brain tissue, confirming that these new routes could also be important in prion infections. Some ectoparasites have been proven to harbour prion rods in laboratory experiments. Prion rods were identified in both fly larvae and pupae; adult flies are also able to express prion proteins. The most common causes of myiasis in cattle and sheep, closely related animals with previous prion infections, are Hypoderma bovis and Oestrus ovis, respectively. Both species of flies present a life cycle very different from human myiasis, as they have a long contact with neurological structures, such as spinal canal and epidural fat, which are potentially rich in prion rods. Ophthalmomyiases in humans is commonly caused by both species of fly larvae worldwide, providing almost direct contact with the central nervous system (CNS). The high expression of the prion protein on the skin and mucosa and the severity of the inflammatory response to the larvae could readily increase the efficiency of transmission of prions in both animals and humans. [source]

The Influence of Rejection Episodes in Recipients of Bilateral Corneal Grafts

AMERICAN JOURNAL OF TRANSPLANTATION, Issue 4 2010
K. A. Williams
We investigated whether a rejection episode in one graft was associated with rejection in the other graft, in recipients with bilateral corneal transplants. In a prospectively maintained, national register of 14 865 followed corneal grafts, 1476 patients with bilateral penetrating corneal grafts were identified. Occurrence of rejection was a risk factor for graft failure (p < 0.0001). Logistic regression was used to calculate the adjusted odds ratio for rejection in one eye following rejection in the other eye. In the subset of 1118 patients with bilateral grafts but no history of previous grafts or rejections in either eye, the adjusted odds ratio for a rejection episode in the first eye following rejection in the second was 3.27 (95% confidence interval, CI 1.85, 5.79; p < 0.001). The adjusted odds ratio was 2.04 (95% CI 1.07, 3.91; p = 0.03) for rejection in the second eye following rejection in the first. The median time between the first rejection episode in one eye and the first rejection episode in the other eye was 15 months. Patients with bilateral corneal grafts who suffer a graft rejection episode in one eye are at significantly greater odds of suffering a rejection episode in the other corneal transplant. [source]

3236: Corneal grafting assisted by wavelength-optimised ultrashort pulser lasers

ACTA OPHTHALMOLOGICA, Issue 2010
TAL MARCIANO
Purpose We realized an innovative device for ocular surgery by ultrafast pulse laser optimised for corneal grafting. Methods We constructed a demonstrator device that reproduces surgical conditions of corneal transplant. It is thus possible to realize with the help of an easy handling automatised interface all the kinds of already existing corneal transplants. Also, in order to maximize the spatial quality of the beam, a wavefront correction system using a deformable mirror module has been added. The Demonstrator contains an erbium fiber laser emitting at 1,6 microns. This laser delivers a beam of a few Joule with pulse duration of 700 femtoseconds and a repetition rate of 100-200 KHz. It includes deformable mirrors permitting horizontal displacements and a wavefront sensor. It also contains the administration system of the laser beam. Results The experiments carried out with a surgical tunable source confirmed the initial assumptions: the penetration depth is limited to wavelengths close to 1 microns. When increasing the wavelength, the drop of the scattering compensates the absorption and therefore the penetration depth is slowly varying when increasing the wavelength. The laser does not penetrate near the maximum of the water absorption band located at 1,45 microns. However, the use of a wavelength of 1,6 micros enables an important increasing of penetration depth (factor 3) while conserving the same energy of current technologies. Conclusion The use of a laser source with a wavelength corresponding to the window of transparency of the cornea (1,65 microns) permits to increase both the penetration depth of an ultrafast laser source and the cut quality. [source]

Longterm survival of transplanted human corneal epithelial cells and corneal stem cells

ACTA OPHTHALMOLOGICA, Issue 4 2005
Maria Egarth
Abstract. Purpose:,To investigate the survival of donor-derived epithelial cells in conventional penetrating keratoplasty (PKP) and in homologous penetrating central limbal keratoplasty (HPCLK). Methods and Patients:,Epithelial cells from 26 eyes of 26 patients were analysed. All cases were sex-mismatched (i.e. the transplant and patient were of different genders). At suture removal more than 1 year post surgery, epithelial cells were obtained by gently wiping the removed sutures on glass slides. The cell samples were analysed using fluorescent in situ hybridization (FISH) of the sex chromosomes. This technique makes it possible to allocate the origin of each cell nucleus to either the donor or the recipient. Results:,All 19 conventional PKPs were clear and seven had donor-derived epithelial cells at suture removal. Five of the seven HPCLK grafts were clear at the time of investigation (365,1355 days post surgery), and donor-derived epithelial cells were found in two grafts. Conclusion:,Harvesting cells from removed sutures in combination with FISH enables the clinical study of cell survival in corneal transplants without jeopardizing functioning grafts. From the limited sample investigated, the following tentative conclusions can be made. Donor-derived epithelial cells can remain in conventional PKP for over 1 year. In combined stem cell and corneal grafts (HPCLK), donor-derived epithelial cells may also be retrieved at 1 year or beyond following surgery but the correlation between their presence and a remaining clear graft is uncertain. [source]