T. Laube

Hintergrund: Untersuchung der Inzidenz und der Risikofaktoren für eine Netzhautablösung nach Katarakt-Operation oder refraktivem Linsenaustausch bei Patienten jünger als 61 Jahre. Methoden: Retrospektive Datenanalyse von 7.886 Patienten (13.925 Augen) nach Katarakt-Operation oder refraktivem[zum vollständigen Text gelangen Sie über die oben angegebene URL]

Retina degeneration is one of the leading causes of blindness nowadays and cannot be cured in most cases. It has been shown that electrical stimulation of retinal ganglion cells can generate visual perceptions and therefore implantable electrode arrays can be possible treatment for these patients. Most implants developed for that purpose use electrode arrays with a size of a few millimeters squared and therefore could restore only a very small field of vision and hardly improve orientation in an unknown environment. In this paper we present results of the development of an implantable electrode array covering about 100 mm(2) of retinal tissue.

The development of a visual prosthesis aims to restore partial vision in patients with diseases which lead to total photoreceptor loss. The wireless power supply for a retinal implant may be realized with electromagnetic induction or with optical energy transfer. The present study investigates the feasibility of a photovoltaic power generation in the intraocular lens (IOL) part of an epiretinal implant for long-term tests in rabbits. IOLs containing an array of photovoltaic cells (PVC) and a light-emitting diode (LED) were implanted into the capsular bag after phacoemulsification in three chinchilla rabbits. Optical energy transfer was established with an infrared laser beam at 850 nm wavelength. Lighting up of the LED proved the functioning of the PVC array. The maximum duration of in vivo functioning of the implant was determined by regular tests involving laser beam application. The explanted microsystems were technically analyzed. Tissues of both eyes underwent routine histological examinations. The lifespan of the microsystems ranged from 14 days to more than 7 months. Final malfunction was caused by PVC defects or by defective contacts between PVC and LED that may originate from the low adhesive strength between the silicone cover and the underlying electronic components. The histological examination showed no alterations of the retinal structure in the treated eyes. The power supply for intraocular microsystems by an array of photovoltaic cells was proven to be feasible in long-term tests in rabbits. An essential prerequisite for a future device is hermetic coating of the electronics.

Hintergrund und Fragestellung: Die phototherapeutische Keratektomie mit dem Excimer-Laser (PTK) wird bei rezidivierenden Hornhauterosionen, oberflächlichen Hornhautdystrophien, zentralen Hornhautdegenerationen, oberflächlichen Hornhautnarben und -irregularitäten mittlerweile weit verbreitet als Therapie eingesetzt. Beim Großteil der Indikationen gibt es nach Ausschöpfung konservativer Maßnahmen, abgesehen von der Hornhautstichelung bei rezidivierenden Erosionen und der Keratoplastik bei Hornhautdystrophien und Hornhautnarben, keine therapeutischen Alternativen. Bisher wurde die PTK bei

The aim of this study was to develop surgical methods for the implantation of a wireless intraocular epiretinal retina implant (EPI RET3) in Göttingen minipigs. This animal model resembles closely the anatomical conditions in humans, and is thus suitable for investigating the EPI RET3 implant as designed for the application in humans. Phacoemulsification and vitrectomy was performed on the right eye of 16 Göttingen minipigs under general anesthesia. The implants, consisting of a receiver module and an electrode array connected via a flexible micro cable, were inserted through a corneoscleral incision. The receiver module was placed into the sulcus ciliaris and the electrode array was fixed onto the retina temporal to the optic disc with a retinal tack. Minipigs were monitored for intra- and postoperative ocular complications. Follow-up times were 3 (seven minipigs) and 12 weeks (nine minipigs). Implantation was successfully performed in all 16 minipigs. The complete implantation surgery required on average 2 hours. Intraoperative findings were a minor hemorrhage of the anterior chamber angle in two eyes, one minor iris hemorrhage, and one minor punctiform retinal hemorrhage, which were all reversible. Postoperatively, the corneoscleral incision showed good wound healing in all eyes. Intraocular reactions included mainly fibrin exudation (six eyes) and formation of iris synechiae with the receiver module of the implants (three eyes). The performed implantation procedures of the intraocular EPI RET3 implant are feasible and reproducible within an acceptable surgical time. The development of inflammatory responses is a specific predisposition of the minipig following any intraocular intervention; nevertheless, the surgical techniques should be further improved to minimize procedure-related reactions. Our results provide a step towards the application of the EPI RET3 system in clinical studies.

Validation of dosimetry and exposition time to an ophthalmic surgeon during radioactive plaque operations. Experimental study in which videotaped operations and dosimetric measurements were used to model dosimetry. We used thermoluminescence detectors for high sensitivity readings in radiation fields. Typical intersurgical mobility was videotaped and distances to the plaque was evaluated. Estimated radiation received by surgeons. All simulated plaque operations have a maximum dose rate of 6 mGy per minute (value in the inner eyeball). Mean dose rate is 2 mGy per minute (average of approximately all measurements). The surgeon's fingers receive a dose from 2 to 6 mSv from plaque operation. Results suggest that radioactive plaque operations are safe for the surgeon but that the time for plaque handling should be minimized. A surgeon should not exceed 100 to 200 operations per year.