This prospective case series found that the Argus II retinal prosthesis is well-tolerated and functional for at least one year.
However, careful patient selection is key to ensuring maximum compliance with the rigorous follow-up schedule. Both patients and medical staff should be prepared for a lengthy, arduous rehabilitation process.
Subjects were six patients with visual acuity of light perception or worse implanted with the Argus II Retinal Prosthesis System (Second Sight Medical Products, Inc.) at a single center.
Implantation was safely performed in all patients. One patient experienced postoperative IOP elevation, which was controlled medically. Another patient had moderate detachment of the choroid, which resolved spontaneously. One patient withdrew from the study.
Wound dehiscence, endophthalmitis or retinal detachment was not observed. All patients were able to locate a bright light on the ceiling and a dark line on the floor after surgery. Performance in square localization tests improved in four patients, and direction of motion improved in three patients. One patient achieved grating visual acuity. Goldmann visual field test results improved in all patients.
The authors note that losing a patient to follow-up is not a trivial matter in this case because the device is an intraocular foreign body and the long-term adverse effects are not well known. It is likely that the patient withdrew due to unfulfilled expectations, despite multiple preoperative patient interviews and a rigorous subject selection process.
They say that implanting physicians must keep in mind that retinal prosthesis patients can be psychologically fragile and are subject to neuropsychiatric disorders. In addition, low vision patients are often affected by visual hallucinations. Therefore, they recommend that retinal prosthesis recipients be followed up by a psychologist, in addition to an ophthalmologist, retinal surgeon and rehabilitation specialist, to help close the gap between reality and unreasonable expectations. Future studies on retinal prostheses should include psychological evaluation results in enrollment criteria.