A Prime Candidate for Curing Central Eye Blindness

The Photovoltaic Retinal Implant Microarray, also known as PRIMA, is a first-of-its-kind ocular chip which gives sight to the blind.  First dreamed of by its creator in 2005, the technology has finally reached maturity and has had its first human trials published in the New England Journal of Medicine. Although the implant only has capacity to restore meaningful sight to those who were able to see before the onset of macular degeneration, the technology seems to promise sight to more people in the future with some more improvement.

Age-related macular degeneration, AMD for short, is the loss of central eye vision due to the erosion of the photo-receptors at the back of the eye. This is a condition that progresses at a rate of 1-2 millimeters a year and is irreversible. Present state of the art medication only slows the progression, but does not reverse the damage. Erosion begins at the center of the eye and progresses outward. There are 2 million affected people in the United States, but this new technological marvel restores sight in black and white for the lost part of the field of vision.

The PRIMA utilizes passive electronics to convert the light energy from an infrared laser beam produced by a glasses-mounted video camera into electric signals your eyes can interpret as vision. The principle that the technology relies upon to function is called the photovoltaic effect, not to be confused with the photoelectric effect. The photovoltaic effect is at play when electrical impulses generate light energy. This effect is the same as that which leads solar panels to convert the sun’s rays into electrical energy.

The PRIMA apparatus includes three parts: the photovoltaic micro chip, the glasses-mounted infrared light and camera combo, and a pocket-size processor. A very small amount of surface area is needed to achieve the desired effect – only 4 square millimeters. The critical size of the small implant works in conjunction with the peripheral vision left over from the AMD along with the tiny chip in the anterior eye in order to facilitate a facsimile of whole-eye vision. Although the passive photovoltaic cell is not powerful enough to make natural light into a significant electric signal, the infrared light beam solves the issue. The laser beam is powerful enough to create an electric impulse but because it is infrared, it does not irritate the user’s eyes or potentially bother others.

The test subjects in the recently published experiment included 38 subjects with AMD, six of which did not follow up for subsequent testing. The small size of the implant and laser beam in conjunction with the movement of the eye makes it hard for the laser to always get the information where it needs to be, but with time and practice, the eyes adjust. Most test subjects were able to read books again after one year of practice using the apparatus. While it is not perfect, the results were good overall, and showed stability of the product over a two year timeframe; the human trials boasted a 2/3rds approval rating, and an improvement in vision up to 20/40.

Further technological improvements could include a gray-scale version for the coming iteration along with some capacity to track the entrance of the eye with the projector mounted on the glasses frame. The mechanics of the actual device are simple and ingenious. There is still much work to be done to change the lives of many with central eye blindness.

In summation, scientists have successfully put the PRIMA implant/glasses to use on human subjects with satisfactory success. While there is much progress to be made in order to ensure greater ease of use and enable the detection of shades of color, this technology already shows great stability in the anterior eye area and promises to become a mainstream way to treat severe AMD in medical patients.

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