[Necrosis and reconstruction of the inferior oblique muscle after removal of a wooden intra-orbital foreign body]. / M. obliquus-inferior-Nekrose mit Rekonstruktion bei intraorbitalem Holzfremdkörper.

A 39-year-old patient presented 3 days after a bicycle accident with a progressive left periorbital inflammatory swelling and diplopia in upgaze. On the day of the accident, a cranial x-ray did not reveal a fracture or an orbital foreign body, and the 2.5 cm skin wound on the left lower eyelid was sutured. For further evaluation, computer tomography) was performed. This did not show a radio-opaque, orbital foreign body. An explorative orbitotomy was carried out and revealed a 3.7 cm long wooden fragment medial to the inferior oblique muscle (OI). The extraconal portion of OI was found to be necrotic. Complete reconstruction of the OI was not possible due to the extent of the necrosis. The residual muscle was fixated to the orbital septum. Recovery was good and the diplopia resolved after 6 months. This case emphasizes the importance of a meticulous inspection of skin wounds with a high risk of remaining wooden foreign bodies and shows the possibility of functional recovery of extraocular muscles following partial reconstruction.

The retina implant--new approach to a visual prosthesis.

Currently, no treatment is available for degenerative diseases of retinal photoreceptors. The patients are faced with a high risk of blindness. Biological approaches failed to prove efficacy. A new concept for the treatment of disorders like retinitis pigmentosa is electrical stimulation at various levels of the visual system. Therefore, devices were fabricated with stimulating electrodes contacting retinal or central neurons to elicit biological activity in these cells. It became possible to fabricate even complex devices with an external power supply encapsulated within biocompatible materials. Animal experiments showed that with implanted prototypes cortical activation could be achieved and first experiments in blind human subject also suggest that vision can be restored, however at present in a very low range of simply identifying spots of light. Further developments and also the continuation of animal experiments are necessary before the clinical application will become a standard procedure.

Biocompatibility tests on the intraocular vision aid IOVA.

Intraocular miniaturized image transmission systems are developed to restore vision in patients with irreversible destruction of the anterior ocular segment (i.e. chemical burns, explosion trauma, trachoma) and high risk for corneal transplantation, provided that the posterior ocular segment is intact. To ensure safety of such a device biocompatibility tests were conducted. In the present study the effects of light and temperature in various intensities and the toxicity of the implanted materials on neural function in the rabbit retina in-vivo was investigated. All tests give encouraging results concerning the feasibility of intraocular miniaturized image transmission systems.

Successful long-term implantation of electrically inactive epiretinal microelectrode arrays in rabbits.

BACKGROUND: In the ongoing discussion concerning the realization of an epiretinal prosthesis for electric stimulation of retinal ganglion cells, long-term fixation of such a device is a crucial question. We evaluated surgical techniques for implantation and fixation of electrically inactive microelectrode arrays (MA) into the retinas of rabbits and secondary tissue reactions to the implant. METHODS: Vitrectomy and laser coagulation of the prospective fixation area were performed in rabbits. Implantation of MAs was performed 3 weeks later in 10 animals. The MA was fixated using retinal tacks. The follow-up included ophthalmoscopy and electrophysiology. At the end of the follow-up, the enucleated eyes were processed for light microscopy using standard procedures and grinding techniques. RESULTS: Nine of 10 rabbits were implanted without serious complications. Clinical and electrophysiologic data through 6 months of follow-up did not indicate any adverse effect of the surgery, the implant, or the tack itself. No change in retinal architecture underneath the implant was found by light microscopy. In these cases, the implant was stable at its original fixation area. In three cases, mild cataract formation was observed, and in one case, a total retinal detachment was found. CONCLUSION: Tack fixation of electrode arrays for electric stimulation of the inner retinal surface seems to be a useful approach in long-term implantation of an epiretinal prosthesis.

Mechanisms of the circadian regulation of beta-adrenoceptor density and adenylyl cyclase activity in cardiac tissue from normotensive and spontaneously hypertensive rats.

Circadian variation in beta-adrenoceptor density and adenylyl cyclase activity was studied in myocardium from normotensive Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR). In SHR cardiac beta-adrenoceptor density was significantly lower than in WKY. This reduction in total beta-adrenoceptors was exclusively due to a loss in the beta 1-subtype. Total and beta 1-adrenoceptor density in ventricles from both strains exhibited significant circadian variation with peaks occurring in the middle of the light and dark periods, whereas the beta 2-subtype did not show rhythmicity. Similarly, stimulation of adenylyl cyclase via total beta-adrenoceptors and via the beta 1-subtype was circadian time dependent, but circadian peaks occurring at the beginning of the light and dark periods were 6 h apart from those in beta-adrenoceptor density. Rhythmicity in the formation of cAMP was observed under basal conditions and after stimulation by isoprenaline or a forskolin derivative, whereas addition of manganese-ions abolished the circadian variation. In conclusion, the present study demonstrates that in ventricular tissue from WKY and SHR circadian rhythms observed in total beta-adrenoceptor density are due exclusively to variations in the beta 1-subtype. Since peaks in cAMP formation coincided with troughs in beta-adrenoceptor number, cAMP mediated phosphorylation of beta-adrenoceptors enhancing their down-regulation, could be involved in the circadian regulation of myocardial beta-adrenoceptor density. Rhythmicity in cAMP formation itself seems to involve coupling of G-proteins, because manganese ions abolished the circadian variation.