The implanted 'visual prosthesis,' directly into the brain, allowed the blind woman to see two-dimensional letters and shapes for the first 16 years.
These remarkable advances in optical prostheses are being made by US researchers. They have published their results, which could revolutionize how we assist those who are blind.
Berna Gomez, 42, developed toxic optic neuropathy. This was a serious medical condition that quickly destroyed her optic nerves, which connect her eyes and brain.
Within a matter of days, Gomez' husband and children had disappeared into the darkness. Her career as a science teacher was over.
Gomez, now 57 years old, made a courageous decision to make this brave choice. Gomez agreed to be the first to receive a tiny electrode with 100 microneedles implanted in her visual region. It would measure approximately 4 mm by 4mm and be removed after six months.
Cortivis Prosthesis, bypasses the eye and optic nerve completely and goes straight to the source of visual perception.
Gomez underwent neurosurgery in Spain to implant the device. He spent the next six month going to the lab for four hours each day to receive training and tests with the prosthesis.
Gomez spent the first two months learning to distinguish between spontaneous pinpricks and spots of light in her brain that she sees occasionally.
Researchers could present her with real visual challenges once she is able to do so.
Gomez claimed that she saw a prick in the light from her prosthesis when an electrode was stimulated. This is known as a "phosphene". The intensity of stimulation can affect the appearance of the spot of light. It could be more bright or less faded, white or sepia-toned.
Gomez was able to see the light spots more easily when two electrodes were stimulated simultaneously. Some stimulation patterns looked more like dots than others.
"I can see it!" Gomez exclaimed after spotting a white line in her head in 2018.
Researchers found vertical lines the most difficult to induce. However, Gomez was able by the end to discriminate horizontal and vertical patterns correctly with a 100 percent accuracy.
In action: The Utah Electrode Array (John A. Moran Eye Centre at the University of Utah).
The authors wrote in their paper that "furthermore, the subject reported to us that our stimulation electrodes gave the percepts a more extended shape when we increased the distance between them."
This suggests that the size and appearance of phosphene is not just a function the number of stimulated electrodes, but also the distribution of those electrodes.
These promising results led to the conclusion of the experiment, where the last month was used for Gomez's final month to test if she could see letters using her prosthesis.
Gomez was able to reliably recognize letters such as I, L C, V, O, and C when up to 16 electrodes were stimulated simultaneously in different patterns. She was able to distinguish between an O and a o.
Although the patterns of stimulation required for the rest are not yet known, the findings suggest that the way electrodes stimulate neurons in the brain can create two-dimensional images.
Gomez wore special glasses with embedded video cameras for the last part of her experiment. The camera captured images and stimulated her brain with different electrode combinations.
Gomez was able to distinguish between the black and white borders on cardboard thanks to her glasses. Gomez could locate a large, white square on either side of a computer monitor. Gomez learned faster the more she practiced.
Although the results are encouraging, they were only available for one subject and took place over six months. The prototype will have to be evaluated with many more patients over longer periods before it can be used in clinical practice.
Similar microelectrode arrays (known as Utah Electrode Arrays) have been used in other studies to control artificial limbs. We know that they are safe at least for the short-term. It's still early days and the technology could experience a gradual decline in functionality within a few months.
Engineers are improving the reliability of these devices but we still need to be able to program the software to interpret the visual input.
Researchers at Baylor College of Medicine in Houston placed a similar device inside a deeper portion of the visual cortex last year. The device was found to help blind people trace simple letters such as W, S and Z. It was tested on five participants, two of whom were visually impaired and three of them were sighted.
Gomez's case showed no evidence that the device could cause neural death, epileptic seizures or other side effects. This is a positive sign and indicates that microstimulation can safely be used to restore vision even for those who have experienced irreversible damage to their optic nerves or retinas.
Bioengineer Richard Normann, University of Utah, says that the research aims to improve mobility for blind people.
It could help them identify people, doors, and cars more easily. It could improve safety and independence. We are working towards that goal.
It seems that only very basic sight can be restored with visual prostheses at the moment. However, we can learn more about the brain and how these devices work in the eyes of both blind and sighted individuals and help us to understand the mechanisms behind complex visual images.
Because of the work done by Gomez, perhaps other patients will one day be able trace the entire alphabet using this prosthesis. The device is already being tested by four more patients.
Gomez stated in a statement made a few years back that "I know that I am blind"
"But I felt like there was something I could do to help others in the future." That feeling is still there."
Gomez is listed as a co-author in the paper. She is credited for her hard work and insight.
The Journal of Clinical Investigation published the study.
