Aid for Low Vision

Hope comes to people with low vision in the form of a device called Nomad,

which uses lasers to ‘paint’ rows of pixels directly onto the retina,

creating a high resolution, full-motion picture.

Low vision is an eye condition caused by macular (macula lutea is a small

yellowish area close to the retina and constitutes the area of maximum visual

acuity) or muscular degeneration, and is difficult to correct with conventional

methods like lenses or laser surgery. People with low vision are able to see,

but find it difficult to read printed material, watch television, etc.

Nomad, developed by a partnership between Microvision and Telesensory, is

based on Microvision’s Retinal Scanning Display (RSD) technology. It’s a

wearable device consisting of two pieces–a display system that you wear on the

head and a control module that you can clip on your belt. Nomad has four basic

components: drive electronics in the control module, light sources, scanners,

and optics.

The control module receives signals from an image source–a computer

(desktop, laptop, or wearable), video camera, television, etc–and processes

them. The processed signals contain information that controls the intensity and

mix of colors and the coordinates to position the individual pixels that make up

the image. The head-worn display directs a pinpoint of low power light to the

eye, which the RSD uses to create and convey one pixel at a time through the

pupil to the retina. If the images are in color, three light sources–red,

green, and blue–are modulated and merged to produce a pixel of the required

color. A horizontal scanner then sweeps the light beam into a row of pixels, and

a vertical scanner moves it up to the next line, where another row of pixels is

painted. Refractive and reflective optical elements project this scanning beam

of light through the pupil and onto the retina to create an image. What the

viewer sees is a 640x400 pixels (VGA) image projected in front of him, as if on

a large video screen.

The device is at the beta stage and is expected to hit the US market this

year. More details available at: www.mvis.com, www.telesensory.com

Pragya Madan