The very large electrode array for retinal stimulation (VLARS)-A concept study.

OBJECTIVE: The restoration of vision in blind patients suffering from degenerative retinal diseases like retinitis pigmentosa may be obtained by local electrical stimulation with retinal implants. In this study, a very large electrode array for retinal stimulation (VLARS) was introduced and tested regarding its safety in implantation and biocompatibility. Further, the array's stimulation capabilities were tested in an acute setting. APPROACH: The polyimide-based implants have a diameter of 12 mm, cover approximately 110 mm2 of the retinal surface and carrying 250 iridium oxide coated gold electrodes. The implantation surgery was established in cadaveric porcine eyes. To analyze biocompatibility, ten rabbits were implanted with the VLARS device, and observed for 12 weeks using slit lamp examination, fundus photography, optical coherence tomography (OCT) as well as ultrasound imaging. After enucleation, histological examinations were performed. In acute stimulation experiments, electrodes recorded cortical field potentials upon retinal stimulation in the visual cortex in rabbits. MAIN RESULTS: Implantation studies in rabbits showed that the implantation surgery is safe but difficult. Retinal detachment induced by retinal tears was observed in five animals in varying severity. In five cases, corneal edema reduced the quality of the follow-up examinations. Findings in OCT-imaging and funduscopy suggested that peripheral fixation was insufficient in various animals. Results of the acute stimulation demonstrated the array's ability to elicit cortical responses. SIGNIFICANCE: Overall, it was possible to implant very large epiretinal arrays. On retinal stimulation with the VLARS responses in the visual cortex were recorded. The VLARS device offers the opportunity to restore a much larger field of visual perception when compared to current available retinal implants.

Pseudophakic retinal detachment in young-aged patients.

OBJECTIVE: To investigate the incidence and risk factors for retinal detachment (RD) after cataract surgery or refractive lens exchange (RLE) in patients aged below 61 years. METHODS: Retrospective medical chart review of 7,886 patients (13,925 eyes) who underwent cataract surgery or RLE. Patients aged below 61 years were selected. Age, gender, axial length, follow-up times, and the occurrence of RD were recorded. Additional characteristics documented for RD cases were: history of RD, preexisting retinal findings, laser capsulotomy, status of macula at RD, date and details of RD. RESULTS: From a total of 421 patients (677 eyes) aged below 61 years 24 cases of RD were identified, resulting in an overall cumulative incidence per eyes of 3.55%. The mean follow-up time was 45 ± 32.8 months. Ninety-two % of all RDs occurred within 3.6 years from surgery. Axial length had a significant effect on the risk of RD after cataract/ RLE surgery (HR = 1.42, P = 0.0001, 95% CI 1.19-1.69). The highest incidence of RD occurred in the subgroup of 25 to 28.9 mm axial length (10.2%). With an increase in age of ten years, the hazard of postoperative RD was not significantly increased by a factor of 1.50 (P = 0.286, 95% CI 0.71-3.15). The highest incidence of RD occurred in patients aged 50-54 years (5.39%). Compared to females, males had an almost twofold not significant risk of postoperative RD (HR = 1.96, P = 0.123, 95% CI 0.83-4.63). None of the RD cases had a history of RD. CONCLUSIONS: Axial length is a significant risk factor for pseudophakic RD. The need for cataract surgery or RLE should be carefully considered in patients with axial lengths between 25 and 29 mm, aged 50-54 years, in males, and in case of preexisting retinal findings.

Massive suprachoroidal hemorrhage: Surgical management and outcome.

OBJECTIVE: To describe options for vitreoretinal surgery in the management of massive suprachoroidal hemorrhage (SCH). METHODS: Visual acuity (VA), ocular findings, timing of surgical intervention, surgical procedures, and outcomes of four patients diagnosed with massive SCH and admitted to the University Eye Clinic Essen were reviewed retrospectively. RESULTS: Four eyes of four patients (mean age, 82 years; range, 74-89 years) were studied. In three cases the occurrence of SCH was related to cataract surgery and occurred intra- or postoperatively. One patient developed spontaneous SCH of unclear origin. Three patients had a history of arterial hypertension; one eye had high myopia, two patients suffered from cardiovascular diseases, and two patients had glaucoma. Postoperative follow up of the patients ranged from 5 to 29.5 months (mean, 19.6 months). Transscleral drainage of SCH was in all cases combined with pars plana vitrectomy, use of heavy liquids (perfluorodecalin) and silicone oil tamponade. The mean time interval from hemorrhage to surgical intervention was 16.5 days (range 5-29 days). Preoperative VA of all eyes was light perception. Two patients achieved a final postoperative visual acuity of 20/20 and 20/320, respectively, one patient improved to hand motion, and one patient resulted in no light perception. CONCLUSIONS: Surgical interventions including transscleral drainage of SCH, vitrectomy, and silicone oil tamponade are valuable options in the management of massive SCH to save the eye and possibly improve the otherwise extreme poor prognosis.

Development of very large electrode arrays for epiretinal stimulation (VLARS).

BACKGROUND: Retinal implants have been developed to treat blindness causing retinal degenerations such as Retinitis pigmentosa (RP). The retinal stimulators are covering only a small portion of the retina usually in its center. To restore not only central vision but also a useful visual field retinal stimulators need to cover a larger area of the retina. However, large area retinal stimulators are much more difficult to implant into an eye. Some basic questions concerning this challenge should be answered in a series of experiments. METHODS: Large area retinal stimulators were fabricated as flexible multielectrode arrays (MEAs) using silicon technology with polyimide as the basic material for the substrate. Electrodes were made of gold covered with reactively sputtered iridium oxide. Several prototype designs were considered and implanted into enucleated porcine eyes. The prototype MEAs were also used as recording devices. RESULTS: Large area retinal stimulator MEAs were fabricated with a diameter of 12 mm covering a visual angle of 37.6° in a normal sighted human eye. The structures were flexible enough to be implanted in a folded state through an insertion nozzle. The implants could be positioned onto the retinal surface and fixated here using a retinal tack. Recording of spontaneous activity of retinal neurons was possible in vitro using these devices. CONCLUSIONS: Large flexible MEAs covering a wider area of the retina as current devices could be fabricated using silicon technology with polyimide as a base material. Principal surgical techniques were established to insert such large devices into an eye and the devices could also be used for recording of retinal neural activity.

Aphakia correction with retropupillary fixated iris-claw lens (Artisan) - long-term results.

PURPOSE: To evaluate the technique, safety, and efficacy of the retropupillary implantation of iris-claw intraocular lenses in a long-term follow-up study. PATIENTS AND METHODS: This retrospective study included 31 eyes of 31 patients who underwent an Artisan aphakic intraocular lens implantation between January 2006 and February 2011 at the University Hospital Essen, Essen, Germany and at the Zentrum für Augenheilkunde PD Dr Laube, Düsseldorf, Germany. Preoperative data collected included demographics, etiology of aphakia, previous surgeries, preoperative eye pathology, intraocular pressure, clinical signs of endothelial cell loss, and best corrected visual acuity. Operative data and postoperative outcomes included the best corrected visual acuity, lens position, intraocular pressure, pigment dispersion, clinical signs of endothelial cell loss, development of macular edema, and other complications. RESULTS: Thirty-one patients were included. The mean follow-up was 25.2 months (range: 4-48 months). The mean best corrected visual acuity postoperatively was 0.64 logarithm of the minimum angle of resolution (logMAR) and varied from 0 logMAR to 3 logMAR. Some patients had a low visual acuity preoperatively because of preoperative eye pathologies. In 22 patients the visual acuity improved, in two patients the visual acuity remained unchanged, and seven patients showed a decreased visual acuity. Complications were peaked pupils (n=10) and retinal detachment in one case. Four patients showed an iris atrophy and high intraocular pressure was observed only in one patient. Subluxation of the intraocular lens, endothelial cell loss, and macular edema were not observed. CONCLUSION: The presented long-term results demonstrate that retropupillary iris-claw lens implantation is a safe and effective method for the correction of aphakia in patients without capsule support. This surgical procedure has the advantages of a posterior chamber implantation with a low intraoperative and postoperative risk profile.

Multicenter, prospective, open-label, observational study of bimatoprost 0.01% in patients with primary open-angle glaucoma or ocular hypertension.

BACKGROUND: Bimatoprost 0.01% was developed for improved tolerability over bimatoprost 0.03%, while maintaining efficacy in lowering intraocular pressure (IOP). This multicenter, prospective, open-label, observational study was designed to investigate the efficacy and tolerability of bimatoprost 0.01% in routine clinical practice. METHODS: Data were collected from 10,337 patients with primary open-angle glaucoma or ocular hypertension attending 1334 centers in Germany. The primary efficacy outcome was mean change in IOP in each eye from baseline to 10-14 weeks after initiation of bimatoprost 0.01%. Target IOP, prior therapies, additional treatments, and adverse events were also assessed. All treatment decisions were at the physicians' discretion. RESULTS: Bimatoprost 0.01% significantly lowered mean IOP from baseline by -4.1 mmHg (P < 0.0001) in all patients after a mean of 10.45 weeks. In patients without previous treatment, bimatoprost 0.01% reduced mean IOP from baseline by -6.5 mmHg (P < 0.0001). Bimatoprost 0.01% also significantly reduced IOP in patients previously treated with monotherapy of ß-blockers, prostaglandin analogs, carbonic anhydrase inhibitors or bimatoprost 0.03%. No adverse events were reported by 93.9% of patients during treatment with bimatoprost 0.01%; the most commonly reported adverse events were eye irritation (2.0%), ocular hyperemia (1.4%), and conjunctival hyperemia (1.2%). Physicians and patients rated tolerability and adherence as high, and most patients said they would continue with bimatoprost 0.01% treatment. CONCLUSION: Bimatoprost 0.01% can produce additional IOP-lowering effects when used in routine clinical practice in patients who have received prior therapy, in addition to lowering IOP in previously untreated patients. A high rate of continuation of therapy with bimatoprost 0.01% was observed in patients who switched from a variety of different medications. The results suggest that bimatoprost 0.01% is a suitable first-choice therapy in patients with primary open-angle glaucoma or ocular hypertension.

Acute electrical stimulation of the human retina with an epiretinal electrode array.

PURPOSE: To determine the threshold charges needed for eliciting visual perceptions through acute electrical stimulation of the human retina in patients suffering from retinitis pigmentosa, using an epiretinal microelectrode array. METHODS: In a multicentre study, 20 patients (average age 55 years) with visual acuities ranging from 4/200 to no light perception were included. The stimulation procedure was performed during a pars plana vitrectomy, for a maximum of 45 min, by using a microcontact film with IrO(x) electrodes connected by cable to a current generator. After repeated stimulation and threshold charge determination, the microelectrode array was removed. RESULTS: Nineteen of 20 patients stated in the postoperative interviews that they experienced one or more visual perceptions with close time correlation to single stimulation events. Minimum threshold charges needed to generate visual perceptions could be measured and verified in 15 patients. The charge level ranged from 20 to 768 nC with single or multiple electrodes. One patient suffered a retinal detachment during the procedure; this patient's retina was successfully reattached. There were no further adverse reactions observed during the 3-month follow-up. CONCLUSION: Acute epiretinal stimulation of the human retina, using a microelectrode array, can elicit visual perceptions in blind patients with retinitis pigmentosa.

Development of surgical techniques for implantation of a wireless intraocular epiretinal retina implant in Göttingen minipigs.

BACKGROUND: 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. METHODS: 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). RESULTS: 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). CONCLUSIONS: 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.

Angiographic findings following tack fixation of a wireless epiretinal retina implant device in blind RP patients.

BACKGROUND: The fixation of polyimide stimulator foils as the basic substrate of epiretinal prostheses by using retinal tacks may cause retinal or choroidal alterations such as retinal proliferations or choroidal neovascularizations. During the prospective trial for the semichronical testing of a wireless intraocular retinal implant (EPIRET3) we investigated alterations in angiographic findings during implantation and after explantation of the device, to detect potential vascular pathologies at the fixation site or elsewhere. METHODS: As the final step of the implantation surgery in six blind patients, the stimulator was placed on the retinal surface using retinal tacks. For the detection of possible morphological or vascular alterations committed by the implant fluorescein angiography (FA) was performed 1 day before and 4 weeks after implantation surgery, as well as at the final visit 5 months after explantation. RESULTS: Following implantation surgery funduscopy and FA did not reveal any evidence of either vascular pathologies or choroidal neovascularisations (CNV), in addition, no cystoid macular edema (CME) occurred after 4 weeks. At the 6-month follow-up visit, we found a mild epiretinal gliosis formation in four patients. In one patient a retinal break occurred during explantation, requiring a temporary silicone-oil endotamponade. At the final visit, we observed a focal proliferative vitreoretinopathy (PVR) reaction without activity, while there was no evidence for a CNV formation in that area. CONCLUSIONS: The FA findings confirm our previous results on the safety of the EPIRET3 system, which was tolerated in all patients but revealed a certain risk profile in regard to the stimulator fixation. While there was no evidence for newly occurred CME or CNV during the follow-up visits, nevertheless gliosis or even PVR reaction at the tack's fixation site suggests the need to develop alternative fixation procedures of epiretinal stimulators.

Surgical Results and Microscopic Analysis of the Tissue Reaction following Implantation and Explantation of an Intraocular Implant for Epiretinal Stimulation in Minipigs.

AIMS: For the purpose of visual rehabilitation of subjects with photoreceptor degeneration, an implantable microelectronic device for epiretinal stimulation was developed. Our study aimed to show whether implantation and explantation could be conducted safely and to investigate tissue compatibility. METHODS: The device was implanted in 5 Göttinger minipigs. Four weeks later, the implant was surgical- ly removed. Histopathological examination that followed aimed at detecting inflammatory or proliferative changes. Stains used were hematoxylin and eosin, leukocyte common antigen, CD68 and glial fibrillary acidic protein. A grinding technique was used to visualize the retinal tissue in conjunction with the retinal tacks. RESULTS: The implantation of the devices was successful in all cases. The explantation was complicated by intraoperative hemorrhages. Complete explantation could only be achieved after modifying the implantation strategy. Histopathology revealed a mild degree of cystic disaggregation of the retina. Immunohistochemically, an increased glial fibrillary acidic protein expression of Müller cells was found, which shows a moderate glial cell activation. Inflammatory cells were absent. Using the grinding technique, tissue adjacent to the retinal tacks showed a mild gliosis. DISCUSSION: The viability of implantation and explantation of the implant in minipigs has been shown. The absence of immunoreactive cells or a considerable glial reaction suggest that the device may be considered safe and suitable for further implantation in humans.

Implantation and explantation of a wireless epiretinal retina implant device: observations during the EPIRET3 prospective clinical trial.

PURPOSE: Visual sensations in patients with blindness and retinal degenerations may be restored by electrical stimulation of retinal neurons with implantable microelectrode arrays. A prospective trial was initiated to evaluate the safety and efficacy of a wireless intraocular retinal implant (EPIRET3) in six volunteers with blindness and RP. METHODS: The implant is a remotely controlled, fully intraocular wireless device consisting of a receiver and a stimulator module. The stimulator is placed on the retinal surface. Data and energy are transmitted via an inductive link from outside the eye to the implant. Surgery included removal of the lens, vitrectomy, and implantation of the EPIRET3 device through a corneal incision. The clinical outcome after implantation and explantation of the device was determined. The implant was removed after 4 weeks, according to the study protocol. RESULTS: Implantation was successful in all six patients. While the anterior part was fixed with transscleral sutures, the stimulating foil was placed onto the posterior pole and fixed with retinal tacks. The implant was well tolerated, causing temporary moderate postoperative inflammation, whereas the position of the implant remained stable until surgical removal. In all cases explantation of the device was performed successfully. Adverse events were a sterile hypopyon effectively treated with steroids and antibiotics in one case and a retinal break in a second case during explantation requiring silicone oil surgery. CONCLUSIONS: The EPIRET3 system can be successfully implanted and explanted in patients with blindness and RP. The surgical steps are feasible, and the postoperative follow-up disclosed an acceptable range of adverse events.

Transmittance characteristics of ultraviolet and blue-light-filtering intraocular lenses.

PURPOSE: To record the spectral transmittance curves of various ultraviolet (UV) and blue-light-filtering intraocular lenses (IOLs), evaluate their UV and blue-light-radiation- absorption capacities, and compare them with those of the natural crystalline lens. SETTING: Department of Ophthalmology, Duisburg-Essen University, Essen, Germany. METHODS: Eight IOLs from 6 manufacturers were evaluated. The transmittance of wavelengths from 200 nm to 800 nm was measured using a high-performance spectrophotometer with a diffuse transmittance accessory through a 1.5 mm aperture. RESULTS: All assessed IOLs provided good UVC (200 to 280 nm) and UVB (280 to 320 nm) protection, but 2 IOLs lacked sufficient UVA (320 to 400 nm) protection. Major differences in the absorption capacities were observed in the blue-light range (400 to 500 nm). CONCLUSIONS: The absorption characteristics of some UV and blue-light-filtering IOLs resembled those of the crystalline lens, but some differed. Long-term clinical trials should be performed to determine how blue-blocking IOLs affect the risk for progression of age-related macular degeneration.

Visualization of the visual cortex in minipigs using fMRI.

Minipigs are widely used to examine physiologic mechanisms under experimental settings. The purpose of our study was to localize the visual cortex of minipigs using visual stimulation in functional magnetic resonance imaging (fMRI). Five male Göttinger minipigs were studied with fMRI during visual stimulation with series of light impulses conducted into the MR cabin via fibre optical wave guides (EPI sequences, block design, 1.5 T clinical routine MR-scanner). Statistics were performed using SPM'99. All minipigs showed activation of the visual cortex due to light stimulation. The activation could be superimposed to T2-weighted structural images with good spatial resolution revealing the exact location of the visual cortex. We were able to localize the visual cortex in minipigs for the first time utilizing fMRI on a routine scanner. However, this may be useful for precise positioning of electrodes or implants or be used as a further uncomplicated non-invasive method in physiologic experiments.

A method and technical equipment for an acute human trial to evaluate retinal implant technology.

This paper reports on methods and technical equipment to investigate the epiretinal stimulation of the retina in blind human subjects in acute trials. Current is applied to the retina through a thin, flexible microcontact film (microelectrode array) with electrode diameters ranging from 50 to 360 microm. The film is mounted in a custom-designed surgical tool that is hand-held by the surgeon during stimulation. The eventual goal of the work is the development of a chronically implantable retinal prosthesis to restore a useful level of vision to patients who are blind with outer retinal degenerations, specifically retinitis pigmentosa and macular degeneration.

Long-term effect of acetazolamide treatment of patients with uveitic chronic cystoid macular edema is limited by persisting inflammation.

PURPOSE: To assess the long-term effect of acetazolamide treatment on patients with cystoid macular edema (CME) in the course of intermediate or posterior chronic uveitis and to define those patients who may particularly benefit from the drug. METHODS: Fifty-two eyes (45 patients) with chronic uveitic CME were treated with acetazolamide at an initial dosage of 500 mg/d. The effect of treatment was assessed by fluorescein angiography, ophthalmoscopy, visual acuity, and Amsler testing. Therapy was withdrawn when CME did not improve at 3 weeks. In cases with CME improvement, the dosage was gradually tapered. RESULTS: The mean follow-up was 3.1 years (minimum, 1.5 years). Two subgroups were identified: group 1, quiescence of uveitis with acetazolamide as the single therapeutic agent (33 eyes); and group 2, chronically active uveitis requiring additional systemic antiinflammatory drugs (19 eyes). In both groups, visual acuity improvement was statistically significant (group 1, P = 0.012; group 2, P = 0.025). In 12 patients with a stable visual acuity gain, the medication dose could be tapered off completely without any recurrent edema shown by fluorescein angiography after a minimum follow-up of 1 year. Sixteen patients required a maintenance dosage, ranging from 125 to 500 mg daily. No major adverse effects of the medication were observed. CONCLUSIONS: During long-term follow-up, low-dose acetazolamide can be a useful therapeutic option for chronic CME in uveitis. The effect was better in patients with quiescence of uveitis than in those with chronically active uveitis. Permanent therapy is not imperative in every case.

X-ray crystal structures of a benzonorbornenyl cation and of a protonated benzonorbornenol.

The crystal structure of the 9-methylbenzonorbornenyl cation Me-1+ shows a relatively strong interaction between the sp(2)-hybridized carbon atom C9 and the aromatic ring (C4a-C9 identical with C8a-C9 = 1.897(10) A). The anion Sb(2)F(11)(-) is refined as rotationally disordered along the Sb...Sb axis. In sharp contrast to the findings about Me-1+, the protonated anti-benzonorbornenol 5+ is essentially an oxonium ion with only weak interaction between the C9 bridge and the aromatic ring despite the fact that it is already a positively charged ion, which upon loss of a water molecule is expected to give the parent cation H-1+. The hydrogen atoms on the oxonium O atom are involved in strong hydrogen bonds to chlorosulfonate anions and probably partially disordered despite the large estimated pK(a) differences between the corresponding acid-base pairs. The experimentally determined cation structures are compared with structures computed by DFT methods. Detailed experimental procedures are given.

Decreased keratocyte death after laser-assisted subepithelial keratectomy and photorefractive keratectomy in rabbits.

PURPOSE: To compare keratocyte loss in the corneal stroma after laser-assisted subepithelial keratectomy (LASEK) and photorefractive keratectomy (PRK) in rabbits. SETTING: Department of Ophthalmology, University of Essen, Essen, and the Institute of Anatomy, University of Bochum, Bochum, Germany. METHODS: Laser-assisted subepithelial keratectomy and PRK were performed in rabbits and studied 1, 3, 10, and 20 days after surgery. Excimer photoablation was done unilaterally with a 6.0 mm ablation zone and an 80 microm depth, equivalent to -6.0 diopters. Keratocyte death was analyzed using DNA fragmentation-detecting terminal deoxynucleotidyl transferase deoxy-UTR-nick end labeling (TUNEL) assay and transmission electron microscopy. RESULTS: Numerous TUNEL-positive keratocytes occurred 1 day after PRK; the number decreased significantly after 3 days. After LASEK, significantly fewer TUNEL-positive keratocytes were noted at the early time points (P<.001 at 1 day; P< or =.05 at 3 days). At 10 days, the number of TUNEL-positive keratocytes decreased in both groups but remained significantly higher after PRK than after LASEK (P<.001). Twenty days after both procedures, no significant signs of keratocyte death were found in the corneal stroma. Transmission electron microscopy revealed few apoptotic keratocytes after LASEK. After PRK, apoptotic keratocytes, characterized by chromatin condensation, apoptotic bodies, and cell shrinkage, were scattered in the stroma. The ultrastructural findings confirmed the results obtained with the TUNEL assay. CONCLUSIONS: Laser-assisted subepithelial keratectomy induced significantly less apoptotic keratocyte death than PRK and promoted wound healing in the acute phase after photoablation. This procedure may offer the possibility of treating higher myopia with a decreased risk for developing wound healing-related complications known to occur after PRK.

Optical energy transfer for intraocular microsystems studied in rabbits.

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Ultraviolet radiation absorption of intraocular lenses.

OBJECTIVES: To record and compare the spectral transmittance curves of intraocular lenses (IOLs) made out of polymethyl methacrylate (PMMA), acrylic, hydrogel, and silicone from different manufacturers; to evaluate their ultraviolet radiation absorption capacities; and to contrast the recorded transmittance curves with that of the natural lens. DESIGN: Experimental study. METHODS: We studied 17 different 21-diopter IOLs. A high-performance spectrophotometer with a diffuse transmittance accessory was employed to measure the transmittance of wavelengths from 200 nm to 800 nm through a 1.5-mm aperture. MAIN OUTCOME MEASURES: Transmittance percentage and 10% transmittance cutoff wavelength. RESULTS: All studied IOLs offered good ultraviolet radiation protection in the ultraviolet C (200-280 nm) and ultraviolet B (280-315 nm) ranges. A number of silicone, PMMA, and acrylic lenses showed different and, at times, only low degrees of absorption in the ultraviolet A (315-400 nm) range. CONCLUSIONS: Intraocular lenses of different compositions have ultraviolet radiation absorption characteristics different from that of the crystalline lens.

[Endogenous bacterial endophthalmitis: a retrospective study on 22 consecutive cases]. / Endogene bakterielle Endophthalmitis: eine retrospektive Studie an 22 konsekutiven Fällen.

BACKGROUND: Cases of endogenous bacterial endophthalmitis were analysed regarding predisposing factors, timing of diagnosis, sources of infection, causative organisms, and visual outcome. The value of an immediate vitrectomy compared to exclusively injected intravitreal antibiotics was evaluated reviewing the literature. METHODS: Records of 22 consecutive cases of the last 9 years with endogenous bacterial endophthalmitis were reviewed. The identified source of infection was treated with systemic antibiotics. All affected eyes were treated with intraocular injection of antibiotics, whenever possible combined with vitrectomy. RESULTS: 90% of the patients had severe predisposing diseases, primarily diabetes mellitus combined with renal insufficiency and urinary tract infection (70%). Diagnoses were made 3.5 days after beginning of symptoms. An average of 75% of the patients had gram-positive and 25% gram-negative bacteria as causative organisms. Most common gram-positive bacteria were Staphylococcus aureus and S. epidermidis. In 73% of all eyes vitrectomy was used as primary treatment. In 57% of the cases the visual outcome was light perception or better (excluding primary enucleations and deceased patients). 7% of the eyes had no light perception, 36% underwent secondary enucleation. Especially in cases of early diagnoses (less than or equal to 2 days) therapy was successful (60% of the patients); in contrast to delayed diagnoses (33%). The literature review suggests that immediate vitrectomy is superior to exclusive intravitreal injection of antibiotics concerning bulb conservation and remaining function. CONCLUSIONS: Immediate diagnosis and therapy are crucial for a positive outcome in this ophthalmological emergency. Immediate pars plana vitrectomy with intraocular antibiotic instillation seems to improve the prognosis of the affected eyes.