Photoreceptors in the eye are the only neurons in the body that can be imaged non-invasively and at high resolution. They are therefore a window into the functionality of the central nervous system, including the brain. Many diseases seem to display subtle indicators about their presence through the photoreceptors in the eyes. To measure these indicators, adaptive optics scanning laser ophthalmoscopes are used, but these devices are large, unwieldy, and very expensive. Moreover, they require the patient to cooperate by sitting calmly in a chair while looking into the device, something that kids are rarely excited about.
Engineers at Duke University have now designed a handheld adaptive optics scanning laser ophthalmoscope that can be used with both adults and children. Moreover, it may be useful for use during neurological surgeries in which monitoring patient response is key.
The new device can provide high resolution images of single photoreceptors of the eye, something that was tested on a dozen adult volunteers and two children under anesthesia. One of the kids was a 31 month old child, the youngest patient to ever be imaged using an adaptive optics scanning laser ophthalmoscope.
To make the device so small, the team digitized the wavefront sensor by replacing it with a special high speed algorithm. “Other researchers have shown that the wavefront sensor can be replaced by an algorithm, but these algorithms haven’t been fast enough to be used in a hand-held device,” said Sina Farsiu, a researchers involved in building the device. “The algorithm we developed is much faster than previously used techniques and just as accurate.”
The algorithm controls a MEMS-based mirror that can quickly bend, as prompted by the algorithm. This is the adaptive optics component that constantly adjusts so that a high quality image is achieved. Because both the algorithm and the mirror are as fast as they are, they can compensate for eye movement as well as any shaking of the arm of the user.
Study in Optica: Handheld adaptive optics scanning laser ophthalmoscope…
Via: The Optical Society…