For patients who lose their vision, artificial and implantable devices like retinal prostheses offer a way forward. But while these prostheses are already somewhat effective, a Korean research team recently discovered a potential way to increase performance even further. By understanding how retinal neural signals change based on disease progression, researchers are able to create more targeted prostheses for patients with retinitis pigmentosa and other retinal degenerative diseases. See their findings in IEEE Transactions on Neural Systems and Rehabilitation Engineering.
Retinitis Pigmentosa
There are multiple subtypes of retinitis pigmentosa, a group of genetic diseases causing retinal degeneration. In fact, over 60 genetic mutations are associated with these forms, which include Bardet-Biedl syndrome, Usher syndrome, and Leber congenital amaurosis. Patients with retinitis pigmentosa experience progressive vision loss from retinal degeneration. However, most patients experience severe vision loss by 40 years old.
Symptoms vary but may include:
- Blurred vision
- Decreased night vision
- Tunnel vision
- Poor color and detail perception
- Vision loss and/or blindness
Learn more about retinitis pigmentosa.
New Findings
Currently, there is no cure for retinal degenerative diseases. These conditions cause photoreceptor cell damage, resulting in vision loss. However, artificial vision from prostheses is possible thanks to the resilience of retinal ganglion cells. On The Conversation, authors Matthew Petoe, Lauren Ayton, and Mohit Shivdasani explain artificial vision:
The devices consist of micro-electrodes surgically placed in or near one eye, along the optic nerve (which transmits impulses from the eye to the brain), or in the brain. [These] stimulate the [still functional] parts of the visual system in someone who has lost their sight [by] using tiny electrical pulses similar to those used in a bionic ear or cochlear implant.
But while current prostheses have been effective in some cases, many do not work for patients. Researchers wanted to understand why. First, they hypothesized that failure (or efficacy) related to disease progression. Within their study, they electrically stimulated neural activities in mice models of retinal degeneration. They found that, in later disease stages, these results became less consistent and beneficial.
Researchers note that consistency is a huge issue. Repetitive electrical stimuli are used in prostheses to create neural signals that tell a person what they are looking at. For example, reading the letter “J” requires different electrical stimuli than reading the word “dog.” At later disease stages, when prostheses are less consistent, someone may be unable to actually understand what they are seeing.
As a result, the researchers note that retinal prostheses may need to become more targeted in the future, or find ways to take retinal degeneration stages into account.
Find the source article here.
