In a world where technological advancements have continuously pushed the boundaries of what is possible, medical science has not been left behind. One remarkable achievement in the field of ophthalmology is the Argus II Retinal Prosthesis System, which has brought hope and improved the quality of life for individuals suffering from retinal degenerative diseases. This groundbreaking technology has provided a glimmer of light in the lives of the visually impaired, offering them the chance to regain some level of visual perception.
What is Argus II retinal prosthesis system?
The Argus II retinal prosthesis system (Second Sight Medical Products, Sylmar, CA, USA) is an epiretinal device approved for implantation in the USA in patients with end-stage retinitis pigmentosa (RP). The device is approved for adult patients 25 years or older with bare light or no light perception vision in both eyes.
The Argus II Retinal Prosthesis System is a sophisticated three-part device designed to restore some degree of vision to individuals who have experienced vision loss due to retinitis pigmentosa. The process involves a careful blend of cutting-edge technology and surgical precision.
Also read : Types of Retinal Hemorrhages and its treatment.
The Argus II Retinal Prosthesis Procedure
1. Implanting the Prosthesis
The journey begins with a surgical procedure, wherein a small electronic device is delicately placed on the patient’s retina. This implant plays a pivotal role in the restoration of vision.
2. The Camera and Video Processing Unit
The second part of the system involves external components. Patients wear a camera mounted on a pair of glasses, which captures images from their surroundings. These images are then processed by a portable video-processing unit (VPU).
3. Wireless Transmission and Stimulation
Here’s where the magic happens: The processed images are wirelessly transmitted to the implant on the patient’s retina. This implant, equipped with an array of microelectrodes, stimulates the living cells in the retina. As a result, the brain interprets these electrical patterns as light.
Learning to See Again
Over time, patients learn to interpret the signals from the Argus II system, allowing them to perceive objects, their surroundings, and, in some cases, even read large-print text. It’s important to note that the vision restored by the Argus II is not the same as natural vision. Instead, it provides black-and-white vision without fine details.
who can have Argus II retinal prosthesis?
The Argus II Retinal Prosthesis System is a beacon of hope for individuals who have little to no vision due to advanced retinitis pigmentosa. However, not everyone is eligible for this groundbreaking procedure. Patients must undergo a rigorous medical screening to ensure there are no other physical reasons that would prevent them from receiving the implant.
Indications for Argus II Implantation
In the United States, the Argus II device is indicated for implantation in patients who meet specific criteria:
- Profound Visual Loss from RP: Candidates for Argus II implantation must have profound visual loss resulting from retinitis pigmentosa.
- Age Requirement: Patients must be adults aged 25 years or older.
- Bare Light or No Light Perception: Candidates should have either bare light perception or no light perception vision in both eyes.
- Prior Useful Vision: Patients must have a documented history of useful vision in the past.
- Pseudophakic or Aphakic: At the time of Argus II implantation, candidates must be either pseudophakic (having artificial lenses) or aphakic (having no natural lenses). Those who require cataract surgery or lensectomy before or during implantation are also eligible.
- Ability to Respond to Electrical Stimulation: If no residual light perception remains, the retina must be able to respond to electrical stimulation. This is typically assessed through a dark-adapted flash test and visual evoked potential (VEP) testing.
- Worse-Seeing Eye: The Argus II is implanted into the worse-seeing eye of the patient.
- Commitment to Post-Implant Clinical Follow-up and Rehabilitation: Candidates must be willing and able to attend post-implant clinical follow-up appointments, device fitting sessions, and engage in visual rehabilitation.
Patient Screening Process
The screening process for potential Argus II candidates is comprehensive and meticulous:
- Diagnosis Verification: Patients are first screened to confirm the diagnosis of retinitis pigmentosa, and individuals with good vision are excluded.
- Light Perception Assessment: Candidates must demonstrate bare light perception or no light perception in both eyes.
- Eye Examination: A thorough eye examination, including assessment of the anterior segment and posterior segment, is conducted. This examination checks for the presence of conditions that might affect the implantation.
- Contraindications: Several ocular conditions are contraindications for Argus II implantation, including extreme axial lengths outside the recommended range, corneal opacification, optic nerve diseases, retinal artery and vein occlusions, retinal detachment, and ocular trauma, among others.
- General Health Assessment: Candidates’ physical health and ability to tolerate general anesthesia for the procedure, which can last up to 4 hours, are evaluated.
- Compatibility Check: Patients with metallic or implantable devices in the head or hearing impairments that could interfere with the Argus II device’s functionality may be excluded.
- Tolerance for Post-Operative Care: Willingness and ability to adhere to post-operative clinical follow-up, device fitting, and visual rehabilitation are essential. Cognitive decline or developmental disabilities that hinder understanding and communication during these processes may be contraindications.
- Managing Expectations: Clear communication about the expectations of the Argus II system is vital to ensure candidates fully understand the benefits and limitations of the device.
Limitations and Realistic Expectations
It’s crucial for prospective patients to understand that the Argus II does not restore complete, natural vision. Instead, it offers a glimpse into the world through black-and-white vision. While this may seem limited, it can significantly improve the quality of life for those who have been living in darkness.
Promising Clinical Trial Results
In June 2015, results from the largest and longest-running clinical trial of the Argus II were announced. The study, which included 30 participants, revealed that visual function had improved in nearly 90 percent of the subjects. Additionally, 80 percent of the participants reported an improved quality of life. Importantly, the device did not fail in any of the cases, although one participant had to have it removed due to damage to a suture tab designed to hold the implant in place.
FDA Approval of Argus II retinal prosthesis for a Special Purpose
The Argus II Retinal Prosthesis System is FDA-approved as a Humanitarian Use Device. This designation is specifically intended for devices that benefit small populations and address rare conditions.
The Argus II retinal prosthesis was approved for use in the European Union in March 2001 and by the US Food and Drug Administration (FDA) on February 14, 2013 after over two decades of research and development.1–3 The FDA approved the device for patients with severe to profound RP, a condition affecting fewer than 4,000 people in the USA each year.4
Can Argus II be implantation if I have rheumatoid retinitis (RP)?
Can Argus II be implanted if I have rheumatoid retinitis (RP)?The Argus II Retinal Prosthesis System is primarily intended for individuals with retinitis pigmentosa, a specific type of retinal degenerative disease. It is not designed for rheumatoid retinitis or other retinal conditions. Patients who wish to receive the Argus II implant must undergo a thorough medical screening to determine their eligibility based on their specific condition. Individuals with retinitis pigmentosa are the primary candidates for this device.
Does Argus II improve vision?
Does Argus II improve vision?
Yes, the Argus II Retinal Prosthesis System does improve vision to some extent. It is designed to restore limited visual perception in individuals who have lost their vision due to advanced retinitis pigmentosa. While the vision it provides is not the same as natural sight, it allows users to perceive light, motion, and basic shapes in their surroundings. This improvement in vision can greatly enhance the quality of life for those who have been living with severe vision loss.
1. Humayun MS, de Juan E, Jr, Dagnelie G, Greenberg RJ, Propst RH, Phillips DH. Visual perception elicited by electrical stimulation of retina in blind humans. Arch Ophthalmol. 1996;114(1):40–46. [PubMed] [Google Scholar]
2. Greenemeier L. FDA Approves First Retinal Implant. Nature. Feb, 2013. [Accessed January 21, 2018]. Available from: http://www.nature.com/doifinder/10.1038/nature.2013.12439.