Transmission electron microscopy of the vitreous body tissue in chronic hemophthalmos

Abstract

136The vitreous body is a bradytrophic tissue. Under physiological conditions, it primarily contains a feltwork of collagen fibres, permeated by mucopolysaccharides, sporadic hyalocytes and up to 80% of water. The vitreous body has a gel-like consistence. Clinical experience shows that prolonged presence of erythrocytes and erythrocyte haemolytic-decay products, containing predominantly trivalent ferric ions, has toxic effects on the vitreous body and on the retina (Ballinger et al., 1999). The abovementioned effect is manifested as the loosening of the vitreous fibrillar network, cellular infiltration and, macroscopically, as liquefaction of the vitreous body. Morphologically, this reaction is manifested as inflammatory cellular infiltration, connective tissue proliferation, and as biochemical changes in the vitreous body and retina. Later on, cicatricial processes develop in which fibrous strips form. Epiretinal membranes, which negatively affect the vitreous body transparency and cause traction detachment, play an essential part in numerous complications of proliferating retinopathies, uveitides, vessel occlusions, traumas, primary detachments, and excessive application of laser coagulations. Moreover, they are a dominating factor in the aetiology of chronic hemophthalmos. Vitrectomy enabled the examination of the vitreous body ultrastructure and biochemical examination in vivo. In our case, the ultrastructure of the vitreous body ultrastructure was examined in a patient with hemophthalmos lasting for several months. MATERIAL AND METHODSA patient aged 65 with right-eye hemophthalmos lasting 6 months was referred to our clinic. The visual acuity of the right eye equalled to light perception, with faulty light projection. On the left eye, the visual acuity was 6/6. Ultrasound examination showed beginning cicatricial changes in the vitreous body, the retina was not detached. The patient was operated on using pars plana vitrectomy, and the material obtained was used for examinations after thickening with ultracentrifugation. The tissues were fixated in 2.5% glutaraldhyde solution in phosphate buffer for 3 hours and post-fixated in 2% solution of osmium tetroxide. After dehydration in rising ethylalcohol concentrations, the specimens were embedded into Durcupan ACM Fluca. Thin and ultra-thin sections were prepared on the ultramicrotome Reichert, Jung Ultracut E. After fixation with uranyl acetate and lead citrate, the ultrathin sections were examined with the FEI Morgagni transmission electron microscope. ABSTRACT: Haemolytic products arising in chronic hemophthalmos cause cellular infiltration, necrosis of the vitreous structure, and fibrous membrane formation. In this process, retinal pigment epithelium plays an important role for its antioxidant properties and the capability to phagocyte the decay products.

Asteroid hyalosis

“…Yazar и соавторы, а также другие исследователи [31][32][33][34][35][36] полагают, что распространенность задней витреальной отслойки значительно ниже у пациентов с астероидным гиалозом, чем у лиц с условно нормальным стекловидным телом. Было высказано предположение о том, что процесс формирования астероидного гиалоза может содействовать предотвращению развития ранних проявлений задней витреальной отслойки [8,[51][52][53][54].…”