Fortschritte der Ophthalmologie : Zeitschrift der Deutschen Ophthalmologischen Gesellschaft最新文献

In corneal cryopreservation and other preservation techniques, the donor tissue post-mortem time is believed to affect endothelial cell survival. In this study, porcine eyes were stored in a moist chamber at 4 degrees C for 2, 4, 8, 32, and 72 h. Then the corneas were subjected to cryopreservation. After thawing, a 24-h interval of organ culture was used as a viability test. The cell density of the central cornea and the percentage of Descemet's membrane denuded of endothelium were determined with vital staining and morphometric methods. Corneas stored 2-32 h before cryopreservation showed no difference in necrotic areas or cell density of surviving endothelium. Corneas stored 72 h before cryopreservation revealed no endothelial cell survival. We conclude that a post-mortem time of up to 32 h before corneal cryopreservation has no influence on endothelial cell survival.

The cholesterol requirements of the lens for the formation of plasma membranes are met by self-synthesis only until early postnatal life. This ability subsequently decreases with increasing age and probably ceases altogether. The cholesterol supply then has to come from exogenous sources. These findings are of great importance for the qualitative assessment of extrahepatic side effects of HMG-CoA-reductase inhibitors given for disturbances of lens transparency. The observation of cataracts in chronic toxicity tests with high doses in beagle dogs suggested that the lens enzyme was also affected by the inhibitor, thus causing cataracts. In contrast to other workers' results, we did not find any activity of HMG-CoA-reductase in our experiments with calf, bovine, dog and rat lenses. Preliminary studies with bovine eyes demonstrate a direct correlation between the cholesterol serum level and the content of the aqueous humor. This shows the importance of the exogenous supply for the lens requirements. A further strong argument is that the use of HMG-CoA-reductase inhibitors in patients with pathologically increased cholesterol level is safe as far as the lens transparency is concerned, as demonstrated in clinical trials.

The purpose of the present study was analysis of the cellular response to glaucoma in the human retina. Retinal strips obtained from two enucleated eyes with therapy-resistant, absolute glaucoma were explanted and cultured in vitro. The morphology of the remaining cell populations was assessed with the DiI method in non-cultured, formalin-fixed retinal tissue from both retinas. We found immunohistochemically identifiable glia cells migrating out from the explants and glial processes formed on the substrate. Labelling of representative retinal areas with the fluorescent dye DiI applied to the nerve fiber layer resulted in delineation of growth cone-bearing glial processes, of occasional non-atrophied ganglion cells, and of amacrines and horizontal cells in deeper layers of the retina. The results demonstrate that glaucoma leads both to selective damage of ganglion cells and to a glial proliferation characterized by the formation of processes both in the retina and following explantation.

Between January 1987 and August 1990, a total of 20 keratoplasties were performed in infants and children in the University Eye Hospital, Düsseldorf, accounting for 4% of all keratoplasties during this period. The indications included malformations of the anterior segment and central corneal opacities, mostly of herpetic or microbial etiology. The ages of the patients varied from 2 weeks to 6 years, and the cases were followed up for an average of 2 years. Five (25%) were treated with the autorotation technique. Visual acuity after surgery was satisfactory, although an irregular astigmatism was found in three cases and one child eventually had to have a contact lens fitted. In view of our encouraging results we recommend that ipsilateral rotational autokeratoplasties should be considered more often for suitable forms of central corneal opacyty, particularly for infants and children.

The influence of grid laser photocoagulation on the central visual field of 15 eyes with diffuse diabetic maculopathy was studied in a prospective clinical trial. Throughout the 3 month follow-up period, visual fields were monitored by static perimetry using a combination of 30-1 and 30-2 programs of the Humphrey Field Analyzer. Statistical analysis of all clinical parameters shows that visual acuity correlates very well with foveal light difference sensitivity. The overall sensitivity of the 30 degrees field, however, does not correlate significantly with either of them. During the follow-up period, patients' subjective vision improved significantly (p = 0.0234); for the overall sensitivity of the 30 degrees visual field there was a trend towards improvement (p = 0.0692). The sensitivities of the central 10 degrees and 3 degrees of the visual fields, of the fovea and visual acuity did not change. The results of the present study suggest that during the first 3 months after grid photocoagulation of diffuse diabetic macular edema, the treatment affects mainly the retina outside the macula. The improvement in patient vision may be due to these changes in the visual field.

The influence of the dose-rate of 106Ru-plaques on tumor response was investigated in an experimental tumor-host system (rhabdomyosarcome R1H of the rat). A highly significant difference in tumor response was observed between tumors treated with the identical total dose (25 Gy) but varying dose rates (1.3 Gy/h vs 6.0 Gy/h). All tumors treated with the low-dose irradiation were locally controlled, whereas only one local tumor was controlled by higher dose irradiation. These unexpected results may be explained by the short overall treatment time with high dose rates, which does not allow sufficient reoxygenation of hypoxic tumor cells. In addition to the total dose, the dose rate should be included in treatment planning for choroidal melanoma brachytherapy, and analysis of the clinical data on this topic seems to be necessary in order to develop new therapy concepts.

In this retrospective study about failures of epiretinal buckling procedures performed over 12 years the causes of failure are analysed. The main ones are: new retinal holes, PVR, wrong localization, and inadequate buckling effect. The aim of this investigation was to find indications of the best technique, with a view to improving the success rate, currently, 80-90%, even further.

Derivatives of nicotinic acid such as beta-pyridylcarbinol play an important role in the therapy of lipoprotein disorders. In 1973, J.D. Gass reported the development of cystoid macular edema provoking metamorphosia during the course of nicotinic acid treatment. The aim of this study was to determine subtle changes in ocular function induced by beta-pyridylcarbinol. We investigated 16 patients prior to and after 6 months of beta-pyridylcarbinol treatment and compared the results of clinical and color vision tests in 9 patients after 2-25 years of continuous beta-pyridylcarbinol treatment. After 6 months, significant blue-yellow color vision changes (total error scores within normal ranges) were detected by the Farnsworth-Munsell 100 hue tests in all patients. One patient demonstrated macular edema. Fluorescein angiography, however, showed no evidence of fluorescein leakage. Beta-pyridylcarbinol treatment lasting for years led to diffuse color vision disturbances (total error score = 195). To the best of our knowledge neither macular edema nor color vision disturbances following beta-pyridylcarbinol treatment have been reported so far.

We investigated ten commercially available tissue culture media in a series of perfusion experiments. Porcine cornea were perfused in groups of 10-15 with the media M 199 Earle, MEM Earle, MEM Hank, DMEM, RPMI 1640, Ham's F-12, BM-86 Wissler. Perfusions were done with and without the addition of 2% fetal calf serum. As a control, BSS PLUS (R) was used. We compared the change in corneal thickness in a 6-h perfusion interval. The corneal endothelium was present after all perfusion experiments. Evaluation of the changes in corneal thickness showed that culture media rich in bicarbonate support the endothelial pumping function. The presence of fetal calf serum had no influence on corneal thickness. The absence of glutathione in the culture media did not result in increased corneal thickness. Medium 199 with Earle salt, BSS Plus, DMEM, RPMI 1640 and Ham's F-12 gave the best results and may be considered possible intraocular irrigation solutions.

Intrastromal ring (ISR) implantation is a promising concept in refractive corneal surgery. In theory, it has two main advantages: eccentric corneal surgery and reversibility after ISR explanation. We present our first experimental data on histobiocompatibility after implantation of a 0.2/1.0 mm vaulted polymethylmethacrylate (PMMA) ISR of 7.5 mm diameter with a specially designed "puzzle lock" using a suction-guided stromal channelling device. Ninety-six rabbit eyes were implanted and enucleated after a 24-h to 8-month follow-up to be period and processed for histology (n = 51), scanning electron microscopy (n = 30) and transmission electron microscopy (n = 9). In this study, the histological data are reported. Two main histopathological phases of stromal reaction were observed: (1) up to 3 months: mild inflammation, mostly mononuclear cell reaction with some macrophages; (2) over 3 months: moderate fibrosis surrounding the ISR filling irregularities of the stromal channel. Mild scarring and rare circumscribed vascularization occurred at the sutured peripheral insertion site of the ISR. Persistent epithelial atrophy without erosion or ulceration was regularly observed over the bulging shoulder of the ISR. There was no significant endothelial surgical trauma due to ISR placement. Major complications occurred in 11 cases (11.5%): stromal abscess starting from the incision (n = 8) and massive neovascularization (n = 3). However, the incidence of complications regressed with improved surgical technique. In conclusion, there is good middle-term tolerance of the PMMA ring with a transparent central cornea.