Over at Hackaday.io, Ebin Philip has written an account of his ophthalmoscope (eye retina scanner) powered by a Raspberry Pi and a camera module. The device, which costs about $400 all-in, has been designed to scan the target eye for Diabetic Retinopathy which is a complication of diabetes causing damage to the retina, eventually leading to blindness. Normally, scanners cost in the region of $10-25k so this is an incredible achievement. You can read a lot more about the device, and some of the science behind it, here.