A group of researchers at MIT have built a surprisingly useful medical addon for the iPhone that apparently can help detect cataracts. The CATRA system is a device that snaps on to the front of the iPhone (or any computer screen, from the look of it), and then uses screen output to monitor and test for cataracts in patients' eyes.
You can watch a video of the device in action below. There's a lot more on the official page about how it all works and what cataracts actually do to the eyes, but the takeaway for us here is that this is a device which can be used with anyone's iPhone at a relatively tiny cost, performing a test that would have likely required much more equipment and expertise in the past.
We've already seen iOS devices become standard operating equipment in many medical settings, and that's exactly because of solutions like this one. According to the project's website, this device is already being used, and there are more devices available, so hopefully this project, along with Apple's devices, will help discover some issues as early as possible.