Scientists have found an unprecedented way to potentially cure blindness caused by degenerative eye diseases. The Argus® II Retinal Prosthesis System is a bionic eye prosthetic that works by stimulating the posterior layer of the retina. While the Argus® II Retinal Prosthesis System has been the first step in treating patients with degenerative eye disease, scientists and medical professionals are still unsure of the extent to which it can restore sight and what diseases can feasibly be cured by bionic eyes. In an early clinical trial, researchers have found that the Argus® II Retinal Prosthesis System is capable of restoring the ability of an individual to detect motion, location of objects, and orientation of grates in patients suffering from retinitis pigmentosa (Dorn 2013). While the implications of this particular study are exciting, the ability to transfer these results to patients with other degenerative eye disease is uncertain and much more research must be conducted to definitively say that the Argus® II Retinal Prosthesis System is able to restore sight to the blind. The study within itself presents issues in the experimental design. Regardless, the results promise a bright future in the field of medicine.
The basic information behind the clinical trial is essential in understanding both flaws and implications of the results made based on experimental data. The clinical trial was performed by a team of doctors: Jessy D. Dorn, Ashish K. Ahuja, and Avi Caspi, all of which are from similar background of education and work. The study was reviewed and edited by researchers that specialize in the field of medicinal studies. While the source of funding for the clinical trial does not present any conflict of interest, as it was achieved through a grant from the National Institute of Health, the published results do address a possible source conflict of interest stemming from the participation of Dr. Dorn, Dr. Caspi, and a research editor involved in the study. All three said contributors were employed by Second Sight Medical Products Inc, which is the company responsible for the manufacturing and distribution of the Argus® II Retinal Prosthesis System. Regardless of this presenting a clear conflict of interest, there is no evidence in the data to suggest that the occupation of contributors led to a misrepresentation of the study (Dorn 2013).
The Argus® II Retinal Prosthesis System is a complex multi-dimensional piece of technology that restores sight to the blind over time. The Argus® II Retinal Prosthesis System works by translating sights an individual sees into chemical signals that the brain can convert to recognizable images. Specifically, the prosthetic stimulates the inner residual retina, the part of the eye that turns light into what the brain interprets as an image, which is the malfunctioning mechanism in most patients suffering from degenerative eye diseases. However, the Argus® II Retinal Prosthesis System relies on the patient’s optic nerve, the part of the eye that carries electrical signals to the brain, to still be functioning and intact, disqualifying it from being able to treat fully blinding diseases such as glaucoma. The Argus® II Retinal Prosthesis System consists of three parts: a camera mounted on glass; a prosthetic eye equipped with video processing, and an electrode array that is implanted in the eye to stimulate the residual retina. These three parts work in unison to restore sight to a patient suffering from extensive blindness over time (Cruz 2016).
In order to test if the Argus® II Retinal Prosthesis System was effective in restoring sight in individuals suffering from retinitis pigmentosa, the researchers and doctors conducted an experiment consisting of motion test. After giving informed consent, thirty blind subjects worldwide received the Argus II prosthetic. Before receiving the implant, each subject was determined to have retinitis pigmentosa, have a visual acuity that qualified as legally blind, and have bare light perception in at least one eye (Dorn 2013). Six months after implantation and being trained to use the prosthetic eye, 28 of the original 30 subjects individually viewed a white bar move across a black screen while sitting 1 foot away from the monitor. After each time the bar disappeared off the screen the subject would draw the direction in which the bar moved onto the interactive screen. Each subject’s test was specifically fixed to their needs and how visually impaired they had been before implantation. Each test consisted of 80 trials with no breaks. Each trial was considered an affirmative trial if the subject reported back a track of light that was within a °15 angle of the true angle of the white line. Eleven of the subjects that had affirmative results in the first run of the experiment consistent with improved visual acuity, were then tested in a second run.
The results of the study were used to draw conclusion about the effectiveness of the Argus® II Retinal Prosthesis System with data being tested using statistical analysis to exclude any extenuating factors from the conclusions. The clinical trial found that 15 of the 28 subjects that underwent the first round of testing had an improvement in the location of objects, the motion of the bar moving across the screen, and the ability to identify the orientation of gratings. Eleven of the subjects that had this improvement were tested again, collectively producing 91% affirmative runs. Statistical analysis for both the first and second trials revealed that there were no extenuating factors, such as age, severity of blindness, bar speed, or months having had the implants, that could be a possible explanation for the results (Dorn 2013).
The greatest flaw of this particular experiment is the way that the researchers obtained their sample of subjects. The journal never expressly says how the subjects were selected and because of the nature of the experiment the only way to obtain willing participants is a volunteer process that yielded a very small sample size. Since it can be implied that the subjects volunteered to undergo the implantation by the affirmation that all subjects gave their informed consent, it is likely that these people were severely blind. The study only includes individuals on the more severe end of the blind spectrum and inadequately represents individuals within the population that may be partially blind. However, this is not entirely the researchers’ fault since there is no other ethical way to perform this clinical trial. While selecting a sample that can translate results to a larger population would be ideal if this clinical trial were to be redone, it would be difficult to randomly select a large number of willing participants. It should also be noted that this study took place in 2010 and therefore, may be slightly outdated.
While this clinical trial produced some promising results despite flaws in the experimental design, there is still much to be done in the testing and refining of the Argus® II Retinal Prosthesis System to ensure it can restore sight to patients affected by a range of degenerative eye diseases. While no outlying factors were found to have accounted for the improvement in the sight of the subjects who had their vision partially restored, further tests must be conducted to definitively conclude that prosthetic eyes are a viable way to treat a range of degenerative eye diseases. Regardless, the future for both the treatment of blindness and technology in the medical field looks very bright.
References:
Dorn JD, Ahuja AK, Caspi A. 2013. The detection of motion by blind subjects with theepiretinal 60-electrode (Argus II) Retinal Prosthesis. JAMA Ophthalmology. 2013;131(2):183–189. doi:10.1001/2013. jamaophthalmol.221 [accessed 2020 Jan 27]; https://jamanetwork.com/journals/jamaophthalmology/article-abstract/1375731
Cruz D, Fukushige E, Luo YH. 2016. The potential of the second sight system bionic eye implant for partial sight restoration. Taylor & Francis. [accessed 2020 Jan 20]; p. 673- 681
