Cataracts can lead to blindness, though it's preventable if you catch them early enough. But for the world's poor--many of whom live in remote regions far from the offices of an opthalmologist--diagnosis is difficult. Which is why MIT's Media Lab has put together  a small portable tool that bolts to a smartphone to do the job, possibly even better than a quick eye exam could.
The standard cataracts test assigns a scale of 1 to 4 for impaired vision--from clear to blind--but the new Catra optics and software does a much more thorough job. A simple "yes, no, blurry" answer is enough to aid the diagnosis, which also maps the part of the lens that's affected.
It actually delivers more info than a doctor needs, since the decision is binary (to replace the damaged lens or not). The tool is likely to be useful when more precise cataract therapies are developed. And because it's so sensitive it can actually help diagnose the very early stages of the disease that a quick scan with traditional gear could miss.
For $5,000 you can get a full slit-lamp system in a doctor's office, but Catra's expected to be much cheaper, and portable to boot. It could help change millions of lives.
[Image: Flickr user ex_magician ]