Assuntos
Bases de Dados Factuais/normas , Coração/diagnóstico por imagem , Medicina Nuclear , Sociedades Médicas , Tomografia Computadorizada de Emissão de Fóton Único/normas , Povo Asiático , Cardiologia , Humanos , Processamento de Imagem Assistida por Computador/normas , Japão , Compostos Radiofarmacêuticos , Tecnécio Tc 99m Sestamibi , Radioisótopos de TálioRESUMO
We examined the vitreous change after the retina was destroyed by photocoagulation. Multiple photocoagulation with continuous-wave xenon or diode laser was used to create coagulated spots with 5 disc diameters near the optic disc in 26 eyes of 13 pigmented rabbits aged four weeks. After clinical observation, the eyes were enucleated at 2 weeks and 3, 4, and 14 months after photocoagulation. The vitreous was stained with fluorescein and examined by slitlamp while immersed in water. The vitreous remained unchanged in 2 eyes at 2 weeks after photocoagulation. A liquefied lacuna of the vitreous had formed anterior to the retinal scar in 20 eyes (83%) at 3, 4, and 14 months after photocoagulation. The liquefied lacuna assumed a columnar shape with its bottom corresponding to the retinal scar in 2 eyes at 14 months after photocoagulation. These results show that localized liquefaction in the posterior vitreous can be induced by fundus photocoagulation. It appeared that the presence of a normal retina is one of the prerequisites of integrity of the vitreous in young rabbit eyes.
Assuntos
Fotocoagulação a Laser/efeitos adversos , Retina/cirurgia , Corpo Vítreo/patologia , Animais , Oftalmopatias/etiologia , Oftalmopatias/patologia , Coelhos , Retina/patologiaRESUMO
We examined the vitreous of 37 eyes of 31 patients with macular holes of various stages. There was no posterior vitreous detachment (PVD) in 18 of 18 impending and 19 of 20 newly formed macular holes. In newly formed macular holes, the operculum was located either at the level of or immediately anterior to the retinal surface. The gel component of the vitreous was always separated from the posterior fundus by intervening liquefied lacuna, simulating PVD. However, the cortical vitreous was located posterior to the liquefied lacuna and remained attached to the retina. PVD failed to develop in all of 15 eyes during the follow-up period of 3 months after formation of a macular hole. The incidence of PVD increased in the eyes with macular holes lasting for 1 year or longer. In our present series, PVD in its classical sense did not contribute to the pathogenesis of macular holes as it developed after formation of the latter. Instead, a subtle anterior displacement of vitreous cortex strictly confined to the area of the fovea seemed to trigger the development of idiopathic macular holes.
