Advertisement

The use of Argus® II retinal prosthesis by blind subjects to achieve localisation and prehension of objects in 3-dimensional space

  • Yvonne Hsu-Lin LuoEmail author
  • Joe Jianjiang Zhong
  • Lyndon da Cruz
Retinal Disorders

Abstract

Background

The Argus® II retinal prosthesis system has entered mainstream treatment for patients blind from Retinitis Pigmentosa (RP). We set out to evaluate the use of this system by blind subjects to achieve object localisation and prehension in 3-dimensional space.

Methods

This is a single-centre, prospective, internally-controlled case series involving 5 blind RP subjects who received the Argus® II implant. The subjects were instructed to visually locate, reach and grasp (i.e. prehension) a small white cuboid object placed at random locations on a black worktop. A flashing LED beacon was attached to the reaching index finger (as a finger marker) to assess the effect of enhanced finger visualisation on performance. Tasks were performed with the prosthesis switched “on” or “off” and with the finger marker switched “on” or “off”. Forty-eight trials were performed per subject. Trajectory of each subject’s hand movement during the task was recorded by a 3D motion-capture unit (Qualysis®, see supplementary video) and analysed using a MATLAB script.

Result

Percentage of successful prehension±standard deviation was: 71.3 ± 27.1 % with prosthesis on and finger marker on; 77.5 ± 24.5 % with prosthesis on and finger marker off; 0.0 ± 0.0 % with prosthesis off and finger marker on, and 0.00 ± 0.00 % with prosthesis off and finger marker off. The finger marker did not have a significant effect on performance (P = 0.546 and 1, Wilcoxon Signed Rank test, with prosthesis on and off respectively). With prosthesis off, none of the subjects were able to visually locate the target object and no initiation of prehension was attempted. With prosthesis on, prehension was initiated on 82.5 % (range 59–100 %) of the trials with 89.0 % (range 66.7–100 %) achieving successful prehension.

Conclusion

Argus® II subjects were able to achieve object localisation and prehension better with their prosthesis switched on than off.

Keywords

Retinitis pigmentosa Outer retinal degeneration Retinal prosthesis Artificial retina Psychophysical testing 

Notes

Acknowledgments

The authors acknowledge financial support from the Department of Health through the award made by the National Institute for Health Research to Moorfields Eye Hospital National Health Service (NHS) Foundation Trust and University College London (UCL) Institute of Ophthalmology for a Specialist Biomedical Research Centre for Ophthalmology.

The authors would also like to thank Dr. Aachal Kotecha for her scientific advice and support in the setup and use of the ProReflex® Motion Capture system (Qualisys, Sweden).

Financial disclosure

The authors have no financial disclosures.

Supplementary material

Supplementary Video

A 3D motion capture video (ProReflex® Motion Capture system, Qualysis) of an Argus® II subject carrying out the prehension task with the retinal prosthesis switched on. At the beginning of the video, the zoomed out view showed the relative positions of the 3 specialised ProReflex® infrared cameras triangulated above the worktop to enable capturing of all the movements within the worktop area. At the start of the task, the subject's hand was positioned at the pre-determined start point (shown as the conjoining point of the x, y and z axis). The subject's thumb, forefinger and wrist were marked with 3 infrared (IR) retro-reflective markers, which were labelled as green, blue and lilac dots respectively. The target object was placed at a random location on the worktop, and was also marked with an IR retro-reflective marker (labelled as the yellow dot). During the task, the subject was instructed to visually locate the target object, reach out and grasp the object, place the object to one side before returning the hand to the start point. The timeline at the bottom of the video showed that for the first 16 seconds, the subject's hand remained at the start point while he was searching for the target object. Once the target object was located, he reached out his hand towards the target and grasped the object between his thumb and forefinger successfully at the 17th second, as shown by the motion capture video. (MPG 6254 kb)

References

  1. 1.
    Humayun MS, Dorn JD, daCruz L et al (2012) Interim results from the international trial of Second Sight's visual prosthesis. Ophthalmology 119:779–788. doi: 10.1016/j.ophtha.2011.09.028 PubMedCentralCrossRefPubMedGoogle Scholar
  2. 2.
    Rizzo S, Belting C, Cinelli L et al (2014) The Argus II Retinal Prosthesis: Twelve-Month Outcomes from a Single-Study Center. Am J Ophthalmol. doi: 10.1016/j.ajo.2014.02.039 Google Scholar
  3. 3.
    daCruz L, Merlini F, Arsiero M et al (2012) Subjects Blinded By Outer Retinal Dystrophies Are Able To Recognize Outlined Shapes Using The Argus(R) Ii Retinal Prosthesis System: A Comparison With The Full Shapes Recognition Task. ARVO Meeting Abstracts 53:5507Google Scholar
  4. 4.
    Dorn JD, Ahuja AK, Caspi A et al (2013) The Detection of Motion by Blind Subjects With the Epiretinal 60-Electrode (Argus II) Retinal ProsthesisBlind Subjects and Motion Detection. JAMA Ophthalmol 131:183–189. doi: 10.1001/2013.jamaophthalmol.221 PubMedCentralCrossRefPubMedGoogle Scholar
  5. 5.
    Zrenner E, Bartz-Schmidt KU, Benav H et al (2011) Subretinal electronic chips allow blind patients to read letters and combine them to words. Proceedings Biological sciences / The Royal Society 278:1489–1497. doi: 10.1098/rspb.2010.1747 PubMedCentralCrossRefPubMedGoogle Scholar
  6. 6.
    Klier EM, Angelaki DE (2008) Spatial updating and the maintenance of visual constancy. Neuroscience 156:801–818. doi: 10.1016/j.neuroscience.2008.07.079 PubMedCentralCrossRefPubMedGoogle Scholar
  7. 7.
    Ahuja AKA, Dorn JDJ, Caspi AA et al (2011) Blind subjects implanted with the Argus II retinal prosthesis are able to improve performance in a spatial-motor task. The British journal of ophthalmology 95:539–543. doi: 10.1136/bjo.2010.179622 PubMedCentralCrossRefPubMedGoogle Scholar
  8. 8.
    Halverson HM (1943) The development of prehension in infants. In: Barker RG, Kounin JS, Wright HF (eds) Child behavior and development: A course of representative studies. McGraw-Hill, New York, pp 49–65CrossRefGoogle Scholar
  9. 9.
    Hohlstein RR (1982) The development of prehension in normal infants. Am J Occup Ther 36:170–176CrossRefPubMedGoogle Scholar
  10. 10.
    Oldfield RC (1971) The assessment and analysis of handedness: the Edinburgh inventory. Neuropsychologia 9:97–113CrossRefPubMedGoogle Scholar
  11. 11.
    Research Randomizer: Free Random Sampling and Random Assignment. In: randomizer.org. http://www.randomizer.org/. Accessed 18 Aug 2013
  12. 12.
    Ahuja AK, Dorn JD, Caspi A et al (2009) The Argus II Retinal Prosthesis Enables Blind Subjects to Identify the Direction of Motion. ARVO Meeting Abstracts 50:4590Google Scholar
  13. 13.
    Clifton RK, Muir DW, Ashmead DH, Clarkson MG (1993) Is Visually Guided Reaching in Early Infancy a Myth? Child Development 64:1099–1110. doi: 10.1111/j.1467-8624.1993.tb04189.x CrossRefPubMedGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • Yvonne Hsu-Lin Luo
    • 1
    • 2
    • 3
    Email author
  • Joe Jianjiang Zhong
    • 1
  • Lyndon da Cruz
    • 1
    • 2
  1. 1.Biomedical Research Centre, National Institute of Health ResearchMoorfields Eye Hospital NHS Foundation TrustLondonUK
  2. 2.Institute of OphthalmologyUniversity College LondonLondonUK
  3. 3.Vitreoretinal ServiceMoorfields Eye Hospital NHS Foundation TrustLondonUK

Personalised recommendations