Safety, effectiveness, and cost-effectiveness of Argus II in patients with retinitis pigmentosa: a systematic review

AIM: To assess the effectiveness, safety, and cost-effectiveness of the Argus II in treatment of the retinitis pigmentosa (RP) patients. METHODS: The ProQuest, Web of Science, EMBASE, MEDLINE (via PubMed) were searched using combinations of the keywords of Argus, safety, effectiveness, bionic eye, retinal prosthesis, and RP through March 2018. The retrieved records were screened and then assessed for eligibility. RESULTS: Totally 926 records were retrieved from the searched databases and finally 12 studies included. The RP patients showed improvements in visual function after receiving the prosthesis, compared to the time before the prosthesis or the time it was off. This was measured by square localization, direction of motion, and grating visual acuity tests. No major adverse effect was reported for the Argus II prosthesis itself and/or the surgery to implement it, but the most frequently reported items were hypotony, and conjunctival dehiscence. The incremental cost-effectiveness ratio (ICER) was calculated to be €14603 per quality-adjusted life year (QALY) in UK and $207 616 per QALY in Canada. CONCLUSION: The available evidence shows that the Argus II prosthesis in RP patients is effective in improvement of their visual function. Some minor adverse effects are reported for the prosthesis. The cost-effectiveness studies show that the technology is cost-effective only at high levels of willingness-to-pay.

One-year anatomical and functional outcomes of the Argus II implantation in Korean patients with late-stage retinitis pigmentosa: A prospective case series study

Purpose: To report the anatomical and functional outcomes of Argus II retinal prosthesis implantation in Korean patients Methods:We included five consecutive patients with end-stage retinitis pigmentosa (RP) who underwent Argus II retinal prosthesis implantation and followed for at least 12 months. The transcorneal electrical evoked response was utilized for patient selection. We used intraoperative optical coherence tomography (OCT) for optimal placement of the array and provided specialized vision rehabilitation training. Morphological evaluation using SD-OCT and functional evaluation using computer-based visual function tests (CVFT), a letter reading ability test, and the Functional Low-Vision Observer Rated Assessment (FLORA) were conducted. Results: Postoperatively, the array was completely apposed to the retinal surface in all eyes except for one eye that had a preexisting macular concavity. Fibrosis-like tissues of ≥ 50-μm thickness developed at the interface in two eyes. All patients showed improvement in CVFT, and could read ETDRS letters at a distance of 50 cm. Three patients could read Korean words. FLORA was improved in all patients, mainly in tasks of visual mobility, daily activities, and social interactions. Conclusions: Along with good anatomical outcomes and specialized rehabilitation practices, recipients of the Argus II implant showed profound improvements in functional vision and mobility.

Effect of the electrode array-retina gap distance on visual function in patients with the Argus II retinal prosthesis

Background Post-implantation visual outcomes in patients with the Argus II Retinal Prosthesis is dependent on a multitude of factors including the positioning of the electrode array on the retina. The purpose of this study is to determine whether the average electrode array-retina gap distance correlates with objective visual function outcomes and sensitivity detection thresholds in patients implanted with the Argus II Retinal Prosthesis. Methods Five patients with implantation of the Argus II Retinal Prosthesis were enrolled in this single-institution retrospective study. Patient demographics were collected from medical records. Visual function data (Square Localization [SL] and Direction of Motion [DOM]) and Optical Coherence Tomography (Cirrus HD-OCT) images were extracted retrospectively from the Argus II Retinal Prosthesis Post-Approval study. Visual function tests were performed with the device OFF and ON at each study visit. Electrode array-retina gap distances were measured at each of the array’s 60 electrodes using the Cirrus HD-OCT software in both the nasotemporal and superoinferior planes. Data was obtained at baseline, and post-operative month 1, month 3, month 6, and year 1. Sensitivity detection thresholds were obtained at the initial programming visit and each reprogramming session. Results Three patients performed significantly better in SL visual function testing with the device ON. Patients that worsened in visual function testing with the device ON in both SL and DOM testing had a statistically significant decrease in performance. The electrode array-retina gap distance was found to effect performance in SL testing in a patient-dependent manner. No effect was found between the electrode-array gap distance and DOM testing or sensitivity detection threshold. Conclusion Our results demonstrate that the electrode array-retina gap distance may affect visual function outcomes in SL testing in certain patients with the Argus II Retinal Prosthesis, and the direction and magnitude of this effect is likely patient-dependent. Furthermore, complete apposition between the electrode array and retina may not always be necessary to achieve optimal visual outcomes.

Effect of the Electrode Array-Retina Gap Distance on Visual Function in Patients with the Argus II Retinal Prosthesis

Background: Post-implantation visual outcomes in patients with the Argus II Retinal Prosthesis is dependent on a multitude of factors including the positioning of the electrode array on the retina. The purpose of this study is to determine whether the average electrode array-retina gap distance correlates with objective visual function outcomes and sensitivity detection thresholds in patients implanted with the Argus II Retinal Prosthesis.Methods: 5 patients with implantation of the Argus II Retinal Prosthesis were enrolled in this single-institution retrospective study. Patient demographics were collected from medical records. Visual function data (Square Localization [SL] and Direction of Motion [DOM]) and Optical Coherence Tomography (Cirrus HD-OCT) images were extracted retrospectively from the Argus II Retinal Prosthesis Post-Approval study. Visual function tests were performed with the device OFF and ON at each study visit. Electrode array-retina gap distances were measured at each of the array’s 60 electrodes using the Cirrus HD-OCT software in both the nasotemporal and superoinferior planes. Data was obtained at baseline, and post-operative month 1, month 3, month 6, and year 1. Sensitivity detection thresholds were obtained at the initial programming visit and each reprogramming session. Results: 3 patients performed significantly better in SL visual function testing with the device ON. Patients that worsened in visual function testing with the device ON in both SL and DOM testing had a statistically significant decrease in performance. The electrode array-retina gap distance was found to effect performance in SL testing in a patient-dependent manner. No effect was found between the electrode-array gap distance and DOM testing or sensitivity detection threshold. Conclusion: Our results demonstrate that the electrode array-retina gap distance may affect visual function outcomes in SL testing in certain patients with the Argus II Retinal Prosthesis, and the direction and magnitude of this effect is likely patient-dependent. Furthermore, complete apposition between the electrode array and retina may not always be necessary to achieve optimal visual outcomes.

Effect of the Electrode Array-Retina Gap Distance on Visual Function in Patients with the Argus II Retinal Prosthesis

Background: Post-implantation visual outcomes in patients with the Argus II Retinal Prosthesis is dependent on a multitude of factors including the positioning of the electrode array on the retina. The purpose of this study is to determine whether the average electrode array-retina gap distance correlates with objective visual function outcomes and sensitivity detection thresholds in patients implanted with the Argus II Retinal Prosthesis. Methods: 5 patients with implantation of the Argus II Retinal Prosthesis were enrolled in this single-institution retrospective study. Patient demographics were collected from medical records. Visual function data (Square Localization [SL] and Direction of Motion [DOM]) and Optical Coherence Tomography (Cirrus HD-OCT) images were extracted retrospectively from the Argus II Retinal Prosthesis Post-Approval study. Visual function tests were performed with the device OFF and ON at each study visit. Electrode array-retina gap distances were measured at each of the array’s 60 electrodes using the Cirrus HD-OCT software in both the nasotemporal and superoinferior planes. Data was obtained at baseline, and post-operative month 1, month 3, month 6, and year 1. Sensitivity detection thresholds were obtained at the initial programming visit and each reprogramming session. Results: 1 of 53 patients had a significant average improvementperformed significantly better in the SL visual function test and 0 of 5 had a significant average improvement in the DOM visual when the testing with the device was ON compared to OFF (p < 0.05). Electrode array-retina gap distance did not show a significant correlation with changes in SL . Patients that worsened in visual function (r = 0.20; p = > 0.05) or DOM visual function (r = -0.18; p = > 0.05). In addition,testing with the device ON in both SL and DOM testing had a statistically significant decrease in performance. The electrode array-retina gap distance did not show a significant correlation with was found to effect performance in SL testing in a patient-dependent manner. No effect was found between the electrode-array gap distance and DOM testing or sensitivity detection threshold (r = -0.01; p = 0.98).. Conclusion: Our results demonstrate that the average electrode array-retina gap distance does not correlate with changes in objectivemay affect visual acuity function or sensitivity detection thresholdsoutcomes in SL testing in a cohort ofcertain patients implanted with the Argus II Retinal Prosthesis. Therefore, and the direction and magnitude of this effect is likely patient-dependent. Furthermore, complete apposition between the electrode array and retina may not always be necessary to achieve optimal visual outcomes.

Phthisis Bulbi in a Retinitis Pigmentosa Patient after Argus II Implantation

Purpose. To report a previously unreported complication of phthisis after Argus II prosthesis implantation in a retinitis pigmentosa (RP) patient. Case. A 61-year-old male with advanced RP presented to the retina clinic. The patient had a history of vitrectomy in both eyes (OU) in Cuba in 1996. Pre-op visual acuity (VA) was no light perception (NLP) in the right eye and light perception (LP) in the left eye. The patient met the criteria for Argus II implantation and elected to proceed with surgery in his left eye in December 2017. The surgical implantation of the Argus II was successful without any complications. On postoperative day 1, his VA was stable at LP. He was satisfied with his ambulatory vision after the electrodes were turned on. Four months after surgery, the patient was complaining of aching pain; he was found to have preseptal cellulitis and was started on antibiotics. This swelling improved over two weeks, but when the patient returned, he had a two mm hyphema associated with mild ocular inflammation without an inciting event or reason on exam. The hyphema was treated and resolved after two weeks. However, one month after the hyphema resolved, at postoperative month six, the patient’s vision in his left eye became NLP and began to demonstrate phthisical changes, including hypotony, Descemet membrane folds, and a vascular posterior capsular membrane. Discussion. The theoretical causes of phthisis bulbi after Argus II implantation include fibrous downgrowth, ciliary shut down due to immune reaction, inflammation, or trauma. While the cause of phthisis in this Argus patient is not certain and possibly multifactorial, it is important to note that phthisis is a possible complication of an Argus II implant, as this patient had no other obvious insult or reason for the phthisical change.