The Wake

The ongoing quest to help the blind see has been a long, arduous endeavor that’s embarked innovation in physics and biology for centuries. Age-related blindness is a problem on the rise – the federal government spent four billion dollars on related remedies in 2005. Ten million Americans face macular degeneration – a figure that is only expected to grow. But we may be on the brink of a breakthrough; researchers are now in the final steps of constructing a wireless microchip to insert in the eye that would ultimately transmit visual information to the brain.

The Boston Retinal Implant Project was founded in the 1980s as a collaboration of the Harvard Medical School, the Massachusetts Eye and Ear Infirmary, and the Massachusetts Institute of Technology. Its initial goal aimed to better understand retinal transmission of information to the brain. As time passed, BRIP focused on a new goal: to develop a prosthetic eye. A new optic implant developed by the consortium aims to achieve just this.

Experiments done with pigs have sometimes failed because their bodies rejected the foreign prosthesis.
Thinner than a strand of hair, the elastic microchip contains 30,000 stimulating transistors that receive wireless information from a coil on a pair of eyeglasses. Meanwhile, a camera on the glasses records its surroundings. Using radiofrequency transmission, the coil converts visual data into a specific pattern of electrical impulses that it sends to a corresponding coil implanted behind the eye. This small electrical current passed on by electrodes transmits stimulation to retinal ganglion cells, which process input to the brain, thus creating the perception of vision.

The BRIP has yet to receive full approval from the Federal Drug Administration and carry out successful implants in humans. So far experiments involving people have been limited to low electrical stimulations of the retina for a few hours at a time. Consequently, blind subjects have reported spotting glimpses of light. Due to the invasive nature of the surgery, researchers are aiming to create the most long-lived prosthesis that utilizes the lowest voltage necessary to reach the stimulation threshold of nerve cells without harming any surrounding tissue.

The delicate retina also contains fluid that could interfere with the positioning of the microchip. Biocompatibility is another point of difficulty – experiments done with pigs have sometimes failed because their bodies rejected the foreign prosthesis. The current vitreoretinal approach involves an ab externo procedure – to create space for the implant, fluid is injected into a pore behind the eye to separate the retina from its surface. Then, the implant is wedged into this spot from the external side of the eye where the flap has been made.

The development of this device is far from completion. Human testing experiences a lag behind the experimental tinkering on the bleeding edge of technology. Research is still needed on how blindness affects neural pathways and brain plasticity – the development and reorganization of the brain in the wake of trauma or disability. It may be a while before blind patients can experience normal vision, but progress is being made at an astonishing rate.