RESUMO
The prevalence of ocular disease and blindness in 2,092 Thai subjects, aged 60 years and over, in 33 communities in the vicinity of Siriraj Hospital, Bangkok was studied. The subjects were examined by a team which consisted of 3-4 ophthalmologists, 6 nurses and a trainee health officer. The history, visual acuity and ocular tension were recorded. The anterior and posterior segments of the eye were assessed by using a portable slit lamp biomicroscope, and a direct and indirect ophthalmoscope. The examination revealed disease of the lens in 1656 cases (79.16%), cornea 852 cases (40.72%), lid 516 cases (24.67%), conjunctiva 462 cases (22.08%), retina 300 cases (14.34%), glaucoma 128 cases (6.12%) and of the optic nerve in 39 cases (1.86%) respectively. There were 66 cases of blindness (3.15%) and 743 cases of low vision (35.5%). The causes of blindness were cataract, glaucoma, late age-related maculopathy, optic atrophy and corneal opacity.
Assuntos
Cegueira/epidemiologia , Oftalmopatias/epidemiologia , Idoso , Idoso de 80 Anos ou mais , Cegueira/diagnóstico , Catarata/diagnóstico , Catarata/epidemiologia , Oftalmopatias/diagnóstico , Feminino , Glaucoma/diagnóstico , Glaucoma/epidemiologia , Humanos , Degeneração Macular/diagnóstico , Degeneração Macular/epidemiologia , Masculino , Prevalência , Tailândia/epidemiologia , Baixa Visão/diagnóstico , Baixa Visão/epidemiologiaRESUMO
The purpose of this study was to determine the mechanical response of the lamina cribrosa (LC) to elevated intraocular pressure (IOP) so as to identify possible mechanisms of optic nerve damage in early glaucoma. Ten pairs of normal human eyes were fixed after 24 hours' exposure to 50 mm Hg pressure (experimental eyes) or 5 mm Hg pressure (contralateral control eyes). Photomicrographs of the central region of the optic nerve head (ONH) were taken to examine the LC morphologically and to measure the dimensions of the LC. It was found that elevated IOP caused the LC to deflect posteriorly without affecting its thickness. The majority of the posterior displacement in the LC occurred near the periphery of the ONH. This shape change is consistent with a model of force distribution within the LC in which shear stresses are dominant; such stresses are maximal at the periphery and minimal at the centre of the ONH. These findings support a model in which mechanical forces, specifically shearing stresses within the peripheral lamina, play a direct role in the pathology of glaucomatous optic neuropathy.
