Assessment of MRI issues for the Argus II Retinal Prosthesis

Weiland, James D.; B, Faraji; Greenberg, Robert J.; Humayun, Mark S.; Shellock, Frank G.

doi:10.1016/j.mri.2011.12.005

Cited by 34 publications

(39 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The MRI compatibility and issues of the Argus II system retinal prosthesis have been previously tested [23,53], and the system has been labeled as an MR conditional device (http://www.mrisafety.com/SafetyInfov.asp?SafetyInfoID=313). …”

Section: Methodsmentioning

confidence: 99%

Visual BOLD Response in Late Blind Subjects with Argus II Retinal Prosthesis

et al. 2016

View full text Add to dashboard Cite

Retinal prosthesis technologies require that the visual system downstream of the retinal circuitry be capable of transmitting and elaborating visual signals. We studied the capability of plastic remodeling in late blind subjects implanted with the Argus II Retinal Prosthesis with psychophysics and functional MRI (fMRI). After surgery, six out of seven retinitis pigmentosa (RP) blind subjects were able to detect high-contrast stimuli using the prosthetic implant. However, direction discrimination to contrast modulated stimuli remained at chance level in all of them. No subject showed any improvement of contrast sensitivity in either eye when not using the Argus II. Before the implant, the Blood Oxygenation Level Dependent (BOLD) activity in V1 and the lateral geniculate nucleus (LGN) was very weak or absent. Surprisingly, after prolonged use of Argus II, BOLD responses to visual input were enhanced. This is, to our knowledge, the first study tracking the neural changes of visual areas in patients after retinal implant, revealing a capacity to respond to restored visual input even after years of deprivation.

show abstract

Section: Methodsmentioning

confidence: 99%

Visual BOLD Response in Late Blind Subjects with Argus II Retinal Prosthesis

et al. 2016

View full text Add to dashboard Cite

show abstract

“…It is worth noting that the Argus II is labeled as MRI Conditional, which means that patients with implants can undergo MRI procedures within certain limits. [64] Indeed, Argus II implantees have been scanned as part of routine medical care. [65] Functional MRI would require activation of the device in the scanner.…”

Section: Biological Researchmentioning

confidence: 99%

Retinal Prosthesis

Weiland

Humayun

2014

IEEE Trans. Biomed. Eng.

Self Cite

180

123

View full text Add to dashboard Cite

Retinal prosthesis have been translated from the laboratory to the clinical over the past two decades. Currently, two devices have regulatory approval for the treatment of retinitis pigmentosa. These devices provide partial sight restoration and patients use this improved vision in their everyday lives. Improved mobility and object detection are some of the more notable findings from the clinical trials. However, significant vision restoration will require both better technology and improved understanding of the interaction between electrical stimulation and the retina. This paper reviews the recent clinical trials, highlights technology breakthroughs that will contribute to next generation of retinal prostheses.

show abstract

“…Owing to the exploratory nature of the study, the recruitment criteria for entry 142 into the Argus® II phase I/II clinical trial was RP patients with logMAR 2.9 143 (bare light perception) vision or worse (Humayun et al, 2012). If visual loss in 144 the eyes was asymmetrical, the worse seeing eye was chosen as the study 145 eye to minimise potential harm to the patient.…”

mentioning

confidence: 99%

“…784 785In summary, the above studies have shown theoretically that while more than 786 600 pixels would allow near normal functioning such as reading and 787 navigation, reasonable visual function could be achieved with far fewer pixels 788(16 x 16 array, 4 grey levels and drop-out rate of less than 30%). The current 789Argus® II Retinal Prosthesis with 6 x 10 pixels would be predicted to provide 790 reasonable navigational and some reading vision -as borne out by some 791 patients from the Argus® II phase I/II clinical trials(Humayun et al, 2012). 792…”

mentioning

confidence: 99%