Weekly news picks: mind control and speedy specs.

There was a lot of medical science news this past week, featuring safer nano-particles for imaging tumours, stimulating the circuits of the brain with light and a potentially faster way of getting your glasses fitted.

Illustration of neurons in the brain
Photo courtesy of Wellcome Images

Researchers at Cape Western Reserve University in the US have been working to improve on existing methods for stimulating neural activity in the brain by embedding nano-particles in the brain tissue and triggering them with light. The semiconductor nano-particles are positioned close to the nerve and activated by exposing them to infrared light. The technique does away with the need for cumbersome and potentially damaging electrodes, which cannot be positioned with the same level of precision. The improvement in control also means that the artificial stimulation of cells is more akin to the natural patterns observed in the brain. The technique may have lead to new therapies for brain injured patients.

The drawback of nano-particles in medicine is their toxicity: they can leave behind traces of heavy metals and their small size prevents the body's own filtration system, the kidneys, from expelling them. There are many promising uses for nano-particles in medicine, notably for revealing and destroying cancerous cells. In an effort to reduce the harmful side-effects of nano-particles, US researchers have manufactured tiny silicon flakes that should be able to accomplish these tasks and then dissolve harmlessly before being removed from the body naturally. In tests on mice, the silicon nano-particles glowed red when illuminated by UV light, revealing cancerous tumours that might otherwise be difficult to see.

Living "dark cells" in the eye
Photo courtesy of University of Rochester

The glow of toxic chemicals in the eye was being exploited in an imaging technique performed by scientists at the University of Rochester, which they hope could lead to a better understanding and early detection of macular degeneration. Behind the light sensing cells of the eye - the photoreceptors - is a layer of "dark cells" which maintain the health of those cells. To get a better look at the dark cells in a living eye, it is necessary to see behind the photoreceptors, so the researchers used the glow of toxins in the cells, which is given off when they're exposed to the right wavelength of light, and then used adaptive optics to get a clear image of them. In a patient with macular degeneration, both dark cells and the photoreceptors they maintain die off. Macular degeneration is one of the most common cause of blindness in old age and it may be possible to treat if the health of the dark cells could be assessed early on, before the damage is done.

Another tool that may soon be available to ophthalmologists is a device being worked on by researchers at the University of Arizona, which uses adjustable fluidic lenses and could speed up the process of determining a patient's eye prescription. By controlling the volume of fluid inside a polymer lens, they demonstrated that it was possible to shape the wavefront of light entering the eye, even correcting for astigmatisms. This could save opticians a lot of time, eliminating the need to place different lenses in front of the patient's eyes until the proper prescription has been determined.

Visit the news page at OpticalFutures.com for more of the latest optics news from across the web.