RESUMO
Diabetic retinopathy (DR) is a microvascular disorder occurring due to the long-term effects of diabetes, leading to vision-threatening damage to the retina. The human body has an elaborate system for managing and regulating the number of key trace metals circulating in the blood and stored cells. Inadequate zinc (Zn) and concurrent excess of copper (Cu) levels are associated with an increased level of oxidative stress, which may aggravate the microvascular lesions in diabetes mellitus. Several studies have revealed a significantly lower serum Zn concentration and increased Cu levels in DR when compared with diabetic patients without retinopathy and normal controls. These abnormalities are correlated with the duration of diabetes and higher levels of HbA1C. Multiple pathological mechanisms are proposed to explain these changes including hyperzincuria associated with polyuria, glycosuria, and proteinuria in diabetic patients, as well as impaired absorption of Zn at the gastrointestinal level. Increased levels of free Cu ions may be attributed to glycation and the release of Cu ions from the Cu-binding sites of proteins. Zn supplements and selective Cu chelators may be useful to alleviate oxidative stress and prevent DR progression.
RESUMO
The purpose of the refractive surgery is to diminish the refractive errors and to obtain a better visual acuity without correction. The study presents the evolution of the refraction after two methods of excimer laser refractive surgery (PRK and LASEK). The results show that these surgical methods are safe and predictable when there are correct indications and well performed interventions.
Assuntos
Ceratectomia Subepitelial Assistida por Laser/métodos , Ceratectomia Fotorrefrativa/métodos , Refração Ocular , Procedimentos Cirúrgicos Refrativos , Adulto , Feminino , Seguimentos , Humanos , Terapia a Laser/métodos , Lasers de Excimer , Masculino , Pessoa de Meia-Idade , Satisfação do Paciente , Resultado do Tratamento , Testes Visuais , Acuidade VisualRESUMO
The first very important step for the refractive surgery is the selection of the patients, because there are situations when the surgery for reducing the diopters can produce complications which are difficult to solve. The investigation of the patients who come for a refractive surgery has many steps and each step has his importance.
Assuntos
Seleção de Pacientes , Procedimentos Cirúrgicos Refrativos , Astigmatismo/cirurgia , Humanos , Hiperopia/cirurgia , Lasers de Excimer , Miopia/cirurgia , Oftalmoscopia/métodos , Ceratectomia Fotorrefrativa/métodos , Erros de Refração/diagnóstico , Segurança , Acuidade VisualRESUMO
The success of the refractive surgery depends of the absence of the incidents during and after the surgery. Any complication can compromise more or less the result of the intervention and make it inefficient or even injurious.