June 2013
Volume 54, Issue 15
Free
ARVO Annual Meeting Abstract  |   June 2013
Acuboost™: Enhancing the maximum acuity of the Argus II Retinal Prosthesis System
Author Affiliations & Notes
  • Jose Sahel
    UMR-S 968, Institut de la Vision, Paris, France
    CHNO des Quinze-Vingts, INSERM-DHOS CIC 503, Paris, France
  • Saddek Mohand-Said
    UMR-S 968, Institut de la Vision, Paris, France
    CHNO des Quinze-Vingts, INSERM-DHOS CIC 503, Paris, France
  • Paulo Stanga
    Manchester Academic Health Science Centre and Centre for Ophthalmology and Vision Research, Institute of Human Development, University of Manchester, Manchester, United Kingdom
    Manchester Vision Regeneration (MVR) Lab, Manchester Royal Eye Hospital, Manchester, United Kingdom
  • Avi Caspi
    Second Sight Medical Products, Sylmar, CA
  • Robert Greenberg
    Second Sight Medical Products, Sylmar, CA
  • Footnotes
    Commercial Relationships Jose Sahel, UPMC/Essilor (P), Second Sight (F); Saddek Mohand-Said, None; Paulo Stanga, OPTOS PLC (F), OPTOS PLC (C), OPTOS PLC (R), TOPCON CORP (F), TOPCON CORP (C), TOPCON CORP (R), SECOND SIGHT (F), SECOND SIGHT (R); Avi Caspi, Second Sight Medical Products, Inc. (C), Second Sight Medical Products, Inc. (P); Robert Greenberg, Second Sight Medical Products, Inc. (I), Second Sight Medical Products, Inc. (E), Second Sight Medical Products, Inc. (P), Second Sight Medical Products, Inc. (S)
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science June 2013, Vol.54, 1389. doi:
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      Jose Sahel, Saddek Mohand-Said, Paulo Stanga, Avi Caspi, Robert Greenberg, Argus II Study Group; Acuboost™: Enhancing the maximum acuity of the Argus II Retinal Prosthesis System. Invest. Ophthalmol. Vis. Sci. 2013;54(15):1389.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract
 
Purpose
 

To demonstrate that magnification and image processing in retinal prosthesis with an external camera and processor can enable a visual acuity well beyond the limit set by theoretical resolution of the implanted array.

 
Methods
 

To date, more than 50 patients blinded by outer retinal dystrophies have received an Argus epi-retinal prosthesis (Second Sight, Sylmar, CA). The Argus II System, which is commercially available in the European Economic Area, is the only retinal implant approved for commercial use in these patients anywhere in the world. In a retinal prosthesis, the retina is stimulated based on the light level in the receptive field of the electrode, directly or (as in the case of the Argus II) via a video camera. As a result, the spatial resolution is nominally set by the number of electrodes and the distance between neighboring electrodes. To date the best nominal acuity achieved has been 20/1260. In the current study, the video image acquired by a high resolution camera was processed before being wirelessly transmitted to the implant. While the field-of-view of the cells in the retina covered by the Argus II array is about 20 degrees diagonally, in the current experiment the subject was able to reduce or magnify the image in a range from 0.4x to 16x using a remote hand-held controller (Logitech R-400). In addition, image enhancement was done by extracting global features in the image. Visual acuity was measured using a grating visual acuity test in which square-wave gratings at four orientations were presented on a computer monitor and subjects were required to report the orientation of the bars within the 5 second time limit. In addition, the subject was asked to read short words from a notebook with 2.3cm letters.

 
Results
 

Using a high magnification of 16x the subject’s visual acuity was measured at 1.0 logMAR (20/200). For the reading task, the subject chose to use 4x magnification and was able to read accurately from a notebook at a distance of 30 cm.

 
Conclusions
 

Variable magnification and other image processing strategies can extend the functionality of a retinal prosthesis beyond the spatial resolution set by the number and spacing of the electrodes. This may prove to be a unique advantage of a retinal prosthesis that employs an external camera and processor, such as the Argus II.

  
Keywords: 696 retinal degenerations: hereditary • 754 visual acuity • 494 degenerations/dystrophies  
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