Introduction:
Loss of eyesight affects millions of people worldwide, which impacts their quality of life. Bionic eyes, or retinal implants, visual prosthesis, or artificial vision systems, are an innovative solution for individuals affected by retinal conditions such as age-related macular degeneration (AMD) and retinitis pigmentosa. Several types of bionic eye implants are in development; however, only a few types are available, and they are suitable only for vision loss caused by specific eye diseases.
What Are Bionic Eyes?
A bionic eye is an electrical visual implant that is surgically placed into the eye. As another prosthesis, it not only provides the physical structure and appearance of an eye, but in individuals with advanced vision loss, it creates a sense of vision by improving light sensitivity. It works inside the existing eye structures to provide electrical stimulation, facilitating visual perception in individuals with retinitis pigmentosa. It contains a pair of camera-equipped glasses connected to electrodes placed in the eyeball, which provide the brain with visual information.
The process of vision begins when light enters the eye. The cornea and lens focus that light onto the retina, which is present in the innermost part of the eyeball. Light-sensitive cells in the retina help convert the focused light into electrical energy, which is then transferred to the brain through the optic nerve. For people with vision loss, there may be interruptions in this process.
Sometimes, the cornea or lens may be diseased or damaged, or the retina may not perceive light. In others, the signal may be disturbed or interrupted somewhere along the visual pathway in the brain. So, different types of bionic eye models focus on different target areas in the visual pathway. But at present, Argus II retinal prosthesis systems are the only approved and commercially available bionic implants.
What Is the Mechanism Behind the Bionic Eyes Functioning?
The Argus II system is behind the mechanism of bionic eyes. It consists of three parts: a pair of glasses, an electrode array, and a converter box. The glasses act as a conduit for the camera, which is like the one in smartphones. The picture from the camera is then transferred into a small, compact converter box that would fit into one's purse or pocket. This converter box passes signals to the electrode array that is surgically implanted into the retina of the affected individual. The Argus II works by skipping over the cells destroyed by retinitis pigmentosa to pass visual signals to the brain. The implant sends light waves to the optic nerve by avoiding the damaged retina pathway.
How Are Bionic Eyes Surgically Implanted?
Bionic eye implantation surgery is a delicate surgical procedure. The surgery is typically performed by a skilled ophthalmic (eye) surgeon in a hospital setting. The surgery to implant the electrodes is not complicated; it takes only a few hours, and patients go home within two days with an implant wrapped around one of their eyes. It is secured by a tiny tack the size of a human hair.
A small incision is created in the eye to access the retina during the procedure. Then a microelectrode array is cautiously positioned on the retina, ensuring optimal contact with the retinal cells. The microelectrode array may be secured using tiny tacks or biocompatible materials to prevent displacement. After the placement of the array, the incision is closed, and the site is allowed to heal.
The patient can undergo a period of post-operative care and rehabilitation after the surgery to optimize their visual outcomes. This post-operative care may include various training sessions to make the patient understand how to interpret the artificial visual perceptions by tuning the new electrodes. The converter box contains different knobs that let the patient increase or decrease various things, like contrast and brightness.
What Are the Indications of Bionic Eyes?
Bionic eye prosthesis is mainly indicated for patients with retinitis pigmentosa, a genetic eye disorder where the light-sensitive cells, known as the “rods” and “cones,” are damaged. The main sign of retinitis pigmentosa is the presence of dark deposits in the retina. The patients with this condition may be completely blind or have only minimal light perception; however, they would have had eyesight in the past. All of the prostheses developed currently require a developed visual cortex. This brain part processes light signals to form images, so affected individuals need eyesight for the devices to work. Additionally, to implant this system one should also have an intact retina. Those who lost their vision due to glaucoma, diabetes, or infection and who had retinal damage cannot use the Argus II system.
What Are the Limitations and Challenges of Bionic Eyes?
Despite the potential benefits of bionic eyes, they also carry multiple challenges and limitations, which include:
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Eye Structure Damage - A skilled eye surgeon should carry out the implantation procedure as it carries risks, like damage to the delicate eye structures and the development of complications such as retinal detachment or infection.
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High Cost - Bionic eyes and associated technologies can be restraining for many patients due to their limited access to those who can afford them or do not have insurance or healthcare system coverage.
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Less Number of Electrodes -The Argus II system helps people recognize light, movement, and shapes. However, it still needs to restore sight to the extent some might hope. This is because, currently, the implant has only 60 electrodes; to visualize naturally, an individual needs about a million.
Conclusion:
Bionic eyes are an approach to restoring vision for individuals with retinal disorders and vision impairments. A sense of vision is created by implanting a device inside the existing eye structures to provide electrical stimulation of the retina, facilitating visual perception in individuals with retinal disease. Bionic eyes offer hope and visualization possibilities for those affected by vision loss. It also holds many challenges and limitations; however, ongoing research and development may further enhance the accessibility, functionality, and affordability of the bionic eye.
