Noting that android 4.0 tablet PCs with camera are $60. I think this Optometrist App could be used at the developing world to diagnose developing worlders so they could get glasses if they like.
The app shows visual test modes. The person just walks ten or twenty feet from the tablet PC then shows it a piece of paper. The app knows how many actual feet away they are from an algorithmic perception of camera image of the paper
Then the App displays the letter Y right side up or upside down, at various sizes (similar to the E chart)
the person then shows the apps camera the side of the piece of paper with a Y on it, with the Y at the same orientation (Y, --<, etc) that is displayed. The app then can tell what their "20/20" number is
to test to see if there is astigmatism, which is lens curvature that is experienced as seeing double, the app just makes a bright [ o ] shape. as well as a [ oo ] shape, then rotates the two circles around clockwise or anticlockwise, the "oclock" that removes the doubling effect also describes astigmatic curvature number, if any.
The person just shows a piece of paper with one or two circles on it to tell the apps camera software when they see well.
thus at places where people earn less than $1 or 2$ a day they have pretty accurate vision diagnoses.-- beanangel, Nov 14 2012 android 4.0 tablet Pcs less than $60 https://www.google....45&biw=1280&bih=907 [beanangel, Nov 14 2012] Tribal people traditionally carry tablet PCs and AK47s http://www.youtube....watch?v=x-EBHv0keeQ(from the beginning of time) [pashute, Nov 19 2012] //The person just walks ten or twenty feet from the tablet PC then // someone nicks their tablet PC.-- MaxwellBuchanan, Nov 19 2012 Good idea. You get a + from me.
But how would the tablet know the size that the image appears on its own screen? Wouldn't differences in tablets cause variation?
My solution: Initially show the camera a mirror at 2 feet, and then do the paper thing at 20 feet. it would calculate the zoom factor from the paper and then use that to analize test paterns it had on its display in the mirror.-- Kansan101, Nov 19 2012 This is a great 3rd world solution, especially since traditionally tribal people walk around with tablet PCs and AK47's.-- pashute, Nov 19 2012 //This is a great 3rd world solution, especially since traditionally tribal people walk around with tablet PCs and AK47's. — pashute, Nov 19 2012//
What does this have to do with AK-47s? Or tribal people?
I have been a lot in a third world nation. Cheap smart phones are shockingly common. Seemingly Maslowe's hierarchy of needs goes like this: breathing-water-food-cell phone-sex-sleep-security- etc.
You will find families with malnourished children who own a smart phone. Seriously. A smart phone gives access to help, employment, etc. They can be real survival tools.-- Kansan101, Nov 19 2012 random, halfbakery