Vitreous body proteins. IV. Proteolytic activity of the vitreous body in pathological conditions of the eye]

Two groups of proteins are present in the vitreous: collagen and non-collagen, deriving probably from the blood serum. The authors examined the proteolytic activity against haemoglobin in the course of some ocular pathological conditions. It was demonstrated that the vitreous digests haemoglobin in the acid division of pH (optimum--3.0-4.5) with various activity dependent on the pathological condition of the eye.     

Pathological conditions of the vitreous body in children after eye injuries]

The material consists of 142 eyes in 138 children aged 2-17 years who sustained contusions and perforating injuries. Pathological changes of the vitreous have been observed in 75 p.c. of cases: haemorrhages, opacities, destructive and fibrous changes and even a total fibrosis of the vitreous with shortening of the anatomical axis of the eye. Vitrectomy was performed in 23 cases with extraction of the foreign body in 11. In eyes with a destruction of the vitreous and with vitreoretinal proliferation a laser photocoagulation of the retina or transscleral cryopexy was performed. It is considered that the prophylactical treatment is indicated in all eyes exhibiting structural changes in the vitreous.     

Prostaglandin E2 in the vitreous body of the normal rabbit eye and after ocular trauma.

Rabbit eyes were enucleated and frozen in liquid nitrogen. The vitreous was removed and analyzed for prostaglandin E2 (PGE2). The mean level (+/- SEM) of PGE2 in the anterior as well as in the posterior vitreous was 0.09 +/- 0.016 ng/ml (n = 12 rabbits). Animals pretreated with indomethacin 15 min before death, in order to prevent the formation of prostaglandin during enucleation, showed in both the anterior and posterior vitreous mean PGE2 levels of 0.04 +/- 0.008 ng/ml (n = 12) which were significantly lower. Ocular trauma such as paracentesis of the anterior chamber, indentation of the sclera or laser photocoagulation in the fundus 1 h before death of the animals did not increase the concentration of PGE2 in the vitreous humor. There is no evidence either for local release of PGE2 from tissues in the fundus of the eye or for diffusion of PGE2 from the anterior chamber into the vitreous humor.     

Regulation of eye size by the retinal basement membrane and vitreous body

PURPOSE: Congenital high myopia is an early-onset enlargement of the eye globes that carries a high risk for retinal detachment. The genetic basis for congenital high myopia has frequently been connected to mutations in genes encoding extracellular matrix proteins of the vitreous body (VB) and the inner limiting membrane (ILM). Why defective or missing VB and ILM proteins lead to an increase in eye size is unknown. The present study introduces the chick embryo as a model to study the role of ILM and VB in regulating eye size. METHODS: The ILM and VB were disrupted by injecting collagenase into the eyes of E5 chick embryos. The digestion of VB and ILM proteins was monitored by Western blot and immunocytochemistry. Eye size was assessed up to 9 days after the enzyme injections. RESULTS: Intraocular injection of collagenase led to the disruption of the ILM and the VB by digesting their collagen constituents. Once disrupted, the ILM and the collagen II fibrillar network failed to regenerate despite continued synthesis of VB and ILM proteins. ILM and VB disruption resulted in eye enlargement of 50% within 4 days. The increase in eye size was greatly reduced by reconstituting the ILM. CONCLUSIONS: The present data show that the ILM and the VB play major roles in the early regulation of eye size. The authors speculate that the integrity of the vitreoretinal border is an important factor in preventing congenital high myopia.     

Pathogenesis of disorders of transparency of the optic media of the eye. III. Quantitative detection of copper in relation to the ultrastructure of the vitreous body in chalcosis

The authors elaborated a new analytical micromethod for the detection of elements in morphologically investigated ultrastructures of the vitreous body. For the investigation of quantitative ultrastructural changes electron microanalysis (EMA) was used, combined with raster electron microscopy (REM). Using this method, the authors proved ultrastructural changes of the vitreous body by selective uptake of copper in the trabecular collagen fibres of the vitreous body in experimental chalcosis. From the results ensues that copper does not diffuse in the vitreous body in a homogeneous manner but aggregates in irregular agglomerations of precipitates and crystals. The different quantitative detection of copper in different parts of the same specimen is according to the authors due to the heterogeneous affinity of ultrastructural portions of the vitreous body for copper.