RESUMO
PURPOSE: To evaluate changes in the donor corneal endothelium in the intact globe and in the in vivo rabbit cornea to characterize more fully the formation of "dark events" without relief images in the endothelial mosaic. METHODS: Six ex vivo human donor corneas in the intact globe and an in vivo rabbit model were used to assess the morphological changes associated with osmotically increasing fluid movement from the anterior chamber into the stroma by specular (SM), confocal (CM), and transmission and scanning electron microscopy (TEM, SEM). RESULTS: After application of hyperosmotic solution on the anterior surface of the cornea, dark events without relief images were observed by SM and CM. In both human and rabbit corneas, SEM showed that apical pores at the Y-junctions between endothelial cells became enlarged. Large subendothelial spaces were observed on Descemet's membrane by TEM with some spaces communicating with the anterior chamber. CONCLUSIONS: The findings suggest that these openings at the Y-junctions may represent intercellular channels that may also act as pathways for the formation of intercellular and subendothelial vacuoles in both the rabbit and human donor corneal endothelium. By virtue of their location, these vacuoles are characterized by lack of relief images as seen with the contact SM.
Assuntos
Endotélio Corneano/ultraestrutura , Adulto , Idoso , Animais , Câmara Anterior/efeitos dos fármacos , Transporte Biológico , Substância Própria/efeitos dos fármacos , Endotélio Corneano/efeitos dos fármacos , Humanos , Soluções Hipertônicas/farmacologia , Microscopia Confocal , Microscopia Eletrônica , Microscopia Eletrônica de Varredura , Pessoa de Meia-Idade , Osmose , Coelhos , Sacarose/farmacologiaRESUMO
The design and use of a new device for obtaining corneoscleral buttons for storage and corneal discs for keratoplasty from neonatal and adult donor eyes is described. The device is simple to use and eliminates most of the difficulties in handling infant donor eyes. It thus minimises the risk of damage to the corneal endothelium and the formation of stretch striae, which reduce the quality of the donor material for transplantation.
Assuntos
Transplante de Córnea/métodos , Recém-Nascido , Oftalmologia/instrumentação , Doadores de Tecidos , Adulto , Córnea/anatomia & histologia , Endotélio Corneano/anatomia & histologia , Humanos , Preservação de Órgãos , Manejo de EspécimesRESUMO
Six human donor corneas were studied with the scanning electron microscope to quantify the hazards to the endothelium during the excision of corneoscleral buttons. Although the number studied was small, it was found that: (1) striae were more numerous in the flaccid, very young, donor corneas (under 1 year old) than in the more rigid adult corneas: (2) iridocorneal endothelial touch can result in loss of the posterior membrane and death of the touched endothelial cells. This corroborates the findings of other investigators. Both findings are important, because these conditions reduce the quality of the donor cornea for transplantation.
Assuntos
Transplante de Córnea , Endotélio Corneano/ultraestrutura , Adolescente , Sobrevivência Celular , Feminino , Humanos , Lactente , Masculino , Microscopia Eletrônica de Varredura , Pessoa de Meia-Idade , Manejo de Espécimes , Doadores de Tecidos , Preservação de TecidoRESUMO
Posterior folds in human donor corneas stored as whole eyes in moist chambers, or isolated in McCarey-Kaufman medium at 4 degrees C, have been studied by light and scanning electron microscopy to determine whether or not endothelial cells on the folds are damaged. Extensive, often irreversible cell damage was found associated with most of the folds. Hence posterior folds in donor corneas are of importance in that they indirectly reduce the quality of the donor cornea for transplantation.
