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Hypotony and the Argus II retinal prosthesis: causes, prevention and management
  1. Stanislao Rizzo1,
  2. Pierre-Olivier Barale2,3,
  3. Sarah Ayello-Scheer3,
  4. Robert G Devenyi4,5,
  5. Marie Noelle Delyfer6,7,
  6. Jean-François Korobelnik6,7,
  7. Aleksandra Rachitskaya8,
  8. Alex Yuan8,
  9. K Thiran Jayasundera9,
  10. David N Zacks9,
  11. James T Handa10,
  12. Sandra R Montezuma11,
  13. Dara Koozekanani11,
  14. Paulo Stanga12,
  15. Lyndon da Cruz13,
  16. Peter Walter14,
  17. Albert J Augustin15,
  18. Lisa C Olmos de Koo16,
  19. Allen C Ho17,
  20. Bernd Kirchhof18,
  21. Paul Hahn19,
  22. Lejla Vajzovic20,
  23. Raymond Iezzi21,
  24. David Gaucher22,23,
  25. J Fernando Arevalo10,
  26. Ninel Z Gregori24,
  27. Peter Wiedemann25,
  28. Emin Özmert26,
  29. Jennifer I Lim27,
  30. Flavio A Rezende28,
  31. Suber S Huang29,
  32. Francesco Merlini30,
  33. Uday Patel30,
  34. Robert J Greenberg30,
  35. Sally Justus31,
  36. Daniela Bacherini1,
  37. Laura Cinelli1,
  38. Mark S Humayun32,33
  1. 1Department of Surgery and Translational Medicine, Ophthalmology, University of Florence, Azienda Ospedaliero-Universitaria Careggi, Florence, Italy
  2. 2Sorbonne Universités, UPMC Univ Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, Paris, France
  3. 3CHNO des Quinze-Vingts, DHU Sight Restore, INSERM-DGOS CIC 1423, Paris, France
  4. 4Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, Ontario, Canada
  5. 5Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
  6. 6Bordeaux Population Health Research Center, team LEHA, UMR1219, Universite de Bordeaux, Bordeaux, France
  7. 7Department of Ophthalmology, Bordeaux University Hospital, Bordeaux, France
  8. 8Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, USA
  9. 9W.K. Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan, USA
  10. 10The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
  11. 11Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, USA
  12. 12Manchester Vision Regeneration (MVR) Lab, Manchester Royal Eye Hospital, NIHR Manchester Clinical Research Facility and Manchester University NHS Foundation Trust, Manchester, UK
  13. 13NIHR Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital, London, UK
  14. 14Department of Ophthalmology, RWTH Aachen University, Aachen, Germany
  15. 15Department of Ophthalmology, Staedtisches Klinikum Karlsruhe, Karlsruhe, Germany
  16. 16Department of Ophthalmology, University of Washington Medicine Eye Institute, Seattle, Washington, USA
  17. 17The Retina Service of Wills Eye Hospital, Mid Atlantic Retina, Philadelphia, Pennsylvania, USA
  18. 18Department of Retina and Vitreous Surgery, Center of Ophthalmology, University of Cologne, Cologne, Germany
  19. 19New Jersey Retina, Teaneck, New Jersey, USA
  20. 20Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina, USA
  21. 21Department of Ophthalmology, Mayo Clinic Minnesota, Rochester, Minnesota, USA
  22. 22Nouvel Hôpital Civil, University Hospital of Strasbourg, Strasbourg, France
  23. 23Laboratoire de Bactériologie (EA-7290), Fédération de Médecine Translationnelle de Strasbourg, Université de Strasbourg, Strasbourg, France
  24. 24Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, USA, Miami, Florida, USA
  25. 25Klinik und Poliklinik für Augenheilkunde, Universitatsklinikum Leipzig, Leipzig, Germany
  26. 26Department of Ophthalmology, Ankara University, Faculty of Medicine, Ankara, Turkey
  27. 27Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, Illinois, USA
  28. 28Department of Ophthalmology, Hôpital Maisonneuve-Rosemont, University of Montreal, Montreal, Quebec, Canada
  29. 29Retina Center of Ohio, South Euclid, Ohio, USA
  30. 30Second Sight Medical Products Inc, Sylmar, California, USA
  31. 31Harvard Medical School, Boston, Massachusetts, USA
  32. 32University of Southern California (USC) Roski Eye Institute, USC Institute for Biomedical Therapeutics, Los Angeles, California, United States
  33. 33Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, California, United States
  1. Correspondence to Professor Stanislao Rizzo, Ophthalmology, Azienda Ospedaliero-Universitaria Careggi, Florence 56124, Italy; stanislao.rizzo{at}

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The Argus II retinal prosthesis (Second Sight Medical Products, Sylmar, CA, USA) is an electronic epiretinal implant designed for use in patients with end-stage retinitis pigmentosa, as well as for other outer retinal degenerative conditions, such as choroideremia, Leber’s congenital amaurosis, Bardet-Biedl syndrome, Usher syndrome and rod–cone disease.1 This device was tested in a clinical trial of 30 subjects in the USA and in Europe to measure the rate of serious adverse events (SAEs) and to assess its effects on functional vision and visual acuity.2–4 Subjects performed better on visual tasks with the device turned on and retained these improvements at 5 years postsurgery.4 Additionally, an acceptable safety profile enabled approval of the device for consumer use by the European regulatory authorities in 2011 (Conformité Européenne (CE) mark) and by the US Food and Drug Administration (FDA) in 2013 (FDA approval).

The implant is composed of an extraocular component, namely, an electronics case and implant coil, as well as an intraocular component involving a 60-electrode array that is tacked over the macula (figure 1). The extraocular and intraocular components are connected by a trans-scleral silicone-coated polyamide electrode cable, and the implantation procedure involves a 5.2 mm pars plana sclerotomy incision to insert the electrode array and the electrode cable into the eye. The sclerotomy is then sutured around the cable and covered by an allograft or autograft material.5

Figure 1

The Argus II retinal prosthesis. Labelled image of the Argus II implant (adapted from Humayun et al2).

As with any system having both intraocular and extraocular components, the trans-scleral electrode cable that traverses the sclerotomy permanently is a high-risk feature of the device, as leakage through the pars plana incision can result in chronic hypotony. The percentages of clinical trial subjects who experienced hypotony were 10.0% at …

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  • Contributors Planning the research and conception or design of the work: SR. Data collection: SR, POB, SAS, RGD, MND, JFK, AR, AY, KTJ, DZ, JTH, SRM, DK, PES, LDC, PW, AJA, LCODK, ACH, BK, PH, LV, RIj, DG, JFA, NZG, PW, EO, JIL, FAR, SSH, FM, UP, RJG, SJ, DB, LC and MSH. Data analysis and interpretation: LCODK, ACH, BK, PH, LV, RIj, DG, JFA, NZG, PW, EO, JIL, FAR, SSH, FM, RJG and SJ. Drafting the article: SR, LC, DB, MSH, SAS, RGD, MND, JFK, AR, AY, KTJ, DZ, JTH, SRM, DK, PES, LDC, PW and AJA. Critical revision and final approval: SR, LC, DB and MSH.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests RGD, SRM, PES, AJA, ACH, PH, LV, EO and SSH are consultants for Second Sight. The authors report no other competing or financial interests in the work.

  • Patient consent for publication Not required.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement All data relevant to the study are included in the article or uploaded as supplementary information.

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