[Open conjunctival revision after XEN45 gel stent implantation as a standardized procedure : A step by step guide. Video article]. / Offene Bindehautrevision nach XEN45-Gel-Stent-Implantation als standardisiertes Verfahren : Eine Anleitung Step by Step. Videobeitrag.

BACKGROUND: After implantation of a XEN gel stent scarring of the conjunctiva with elevation of the intraocular pressure (IOP) is a frequent occurrence. This article describes a surgical revision technique with opening of the conjunctiva and removal of scar tissue. In order to standardize the technique the surgical procedure was divided into nine steps. These steps are shown in the video and a series of images. METHODS: Surgery is divided into nine steps: 1) corneal traction suture and topical application of suprarenin, 2) opening of the conjunctiva along the limbus, 3) preparation posteriorly towards the fornix, 4) separation of the stent from the surrounding scar tissue, 5) precise preparation of the stent, 6) removal of additional scar tissue not adhering to the stent, 7) functional testing of the stent, 8) mitomycin C application, 9) closing of the conjunctiva with two corner sutures on the limbus. RESULTS: After surgery a diffuse filtering bleb is formed. In the literature increased success rates up to 90% (criterion: no further surgery necessary) after open conjunctival revision have been described. Severe side effects are not to be expected and are comparable to those of primary surgery. CONCLUSION: Open revision of the conjunctiva after XEN gel stent implantation leads to an effective and enduring lowering of IOP. Revision surgery can be carried out even after a long time period and can keep the patient free of antiglaucomatous drops. Experience in surgery of filtering blebs is advantageous when performing open revision of the conjunctiva.

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.

Intraocular Degradation of XEN45 Gel Stent 3 Years After its Implantation.

INTRODUCTION: We report a case of XEN45 Gel Stent removal 3 years after its implantation. The stent had degraded with a closed lumen, so a new stent was implanted. CASE REPORT: A 63-year-old woman was scheduled for XEN45 Gel Stent implantation. Three years after the primary surgery and 2 years after a surgical revision, second revision surgery was required. The conjunctiva was opened, and the implanted XEN Gel Stent was stripped of the adhesive scar tissues. No aqueous humor flow was seen through the stent, and therefore, the stent was removed. The intrascleral and intracameral parts had degraded. The surface of the stent was irregular and cobbled. A part of the lumen in the middle of the stent had closed. DISCUSSION: We detected changes in the stent after its removal during the surgical revision with conjunctival opening, which is our standard approach for failed XEN Gel Stents. Most surgeons advise needling of the stent in cases of failure. However, in cases of needling, changes in the stent might not have been detected. Thus, the number of patients with similar changes as this report might be higher than the publications suggest. No unique characteristics distinguished this patient from those who had a functional XEN Gel Stent. The stent, in this case, might have been of inferior quality as an exception, or all stents might degrade over time. Therefore, gonioscopy should be performed carefully to detect any changes in the stent. In cases of suspected stent degradation, we recommend a revision surgery with conjunctival opening and removal of the stent in cases of degradation.

The XEN45 Gel Stent as a minimally invasive procedure in glaucoma surgery: success rates, risk profile, and rates of re-surgery after 261 surgeries.

PURPOSE: The XEN45 Gel Stent is a flexible hydrophilic tube placed under the conjunctiva via the anterior chamber. This study investigates the IOP (intraocular pressure)-lowering potential, the risk profile, and the success rate of the XEN45 Gel Stent. METHODS: Two hundred and sixty-one eyes underwent surgery. The mean follow-up time was 8.5 months. The aim of the treatment was to achieve adequate IOP reduction without medication. Therefore, all patients who did not show sufficiently reduced IOP underwent a surgical revision with opening of the conjunctiva. To determinate the success rate, we carried out two kinds of analysis: 1) the primary success rate: eyes with appropiate IOP control without medication or surgical revision, and 2) overall success rate: one surgical revision was allowed. RESULTS: Intraocular pressure was lowered from 24.3 mmHg (SD 6.6) to 16.8 mmHg (SD 7.6), and the medication score was lowered from 2.6 (SD 1.1) to 0.2 (SD 0.7). Revisional surgery was performed in 80 eyes (34%). After a first revision, intraocular pressure was lowered to 14.0 mmHg (SD 5.1), and the medication score was lowered to 0.2 (SD 0.6). The primary success rate was 66% and the overall success rate 90%. The primary success rate was higher in pseudophakic eyes (73%) than in phakic eyes (53%) or combined surgery (55%). CONCLUSIONS: We conclude from our data that the XEN45 Gel Stent has an IOP-lowering potential and few side-effects. Pseudophakic eyes seem to have a better primary prognosis compared to combined surgery or surgery in phakic eyes.

Vitrectomy with and without encircling band for pseudophakic retinal detachment: VIPER Study Report No 2-main results.

BACKGROUND: It is unclear whether or not an additional encircling band improves outcome in vitrectomy for pseudophakic retinal detachment (PRD). Also unclear is whether small gauge transconjunctival trocar-guided vitrectomy is as successful as conventional 20 gauge (G) vitrectomy. METHODS: 257 adult patients with uncomplicated PRD were enrolled in 14 vitreoretinal centres across Germany. Contingent on availability of qualified surgeons, eligible patients were randomly assigned either (i) with ratio 1:1 to 20 G vitrectomy plus encircling band (group E1) or 20 G vitrectomy without any buckle (group C) or (ii) with ratios 1:1:1 to group E1, C or 23/25 G vitrectomy without any buckle (group E2). Treatment success was defined as no indication for any retina reattaching procedure during the follow-up of 6 months. RESULTS: Success was reached in 79.0% (=79/100, group E1) versus 73.5% (=72/98, group C) (p=0.558, OR 1.32, 95% CI 0.65 to 2.65. In group E2 87.7% (=50/57) of patients reached success compared with 78.7% (=48/61) in group C, demonstrating non-inferiority of E2 to C regarding the prespecified margin of 0.8 (OR scale; p=0.05, OR 2.17, 95% CI 0.80 to 5.89). Best corrected visual acuity significantly increased after surgery independent of technique, that is, on average -0.7 (from 1.0 to 0.3) logMAR. Patients suffered from a shift in spherical refraction of -1.0 D in group E1 compared with -0.1 D in group C. Similarly, intraoperative complications (15.2% vs 8.8% of patients) and serious adverse events (30.3% vs 22.5% of patients) were more frequent in group E1. CONCLUSIONS: Vitrectomy with gas is an efficient and safe treatment for uncomplicated PRD. An additional encircling band does not significantly reduce the risk for any second procedure necessary to reattach the retina in 20 G vitrectomy. Small gauge transconjunctival vitrectomy is not inferior to the conventional 20 G technique. TRIAL REGISTRATION NUMBER: DKRS 00003158, Results.

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.

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.

Cortical activation via an implanted wireless retinal prosthesis.

PURPOSE: To demonstrate local cortical activations in the primary visual cortex of the cat as a result of retinal electrical stimulation by means of a completely wireless-controlled, implantable retinal prosthesis in a series of acute experiments. METHODS: The transfer of energy to drive the device and signals to activate any combination of 25 retinal electrodes was achieved completely wirelessly by an external transmitter positioned in front of the eye. Individually configured electrical stimuli were applied via any combination of 25 electrodes, on sending the necessary pulse parameters to the implant. Placement of the implant onto the retinal surface was achieved after lensectomy and vitrectomy in the cat. Fixation was performed with a retinal tack. Cortical activation patterns were recorded by means of optical imaging of intrinsic signals. RESULTS: Implantation and fixation were successfully performed in three cats. Wireless activation of the implant by radiofrequency was demonstrated by recording of stimulus artifacts from the sclera. Local activation of the visual cortex measured by optical imaging of intrinsic signals revealed a shift of cortical response that was well correlated with a change in the position of the activated retinal electrodes. CONCLUSIONS: The results demonstrate the retinotopic activation of the visual cortex using a completely wireless, remote-controlled retinal implant.