Now, get your eye exam on a smartphone

A new smartphone-assisted gadget that can examine your eyes in the comfort of your home without the presence of a doctor has developed.
The USD 75 service called Blink can be administered by a technician who uses a trio of handheld devices.
The screening process takes about 20 minutes, said David Schafran, cofounder and chief product officer for Blink.
In case the user needs an eyeglass prescription, the technician will send results of the screening to an optometrist, who will send back a prescription within 24 hours, according to MIT Technology Review.
Developed by the US start up EyeNetra, Blink's eye exam tools include a black device which takes the place of an autorefractor for measuring the level of focusing error.

The device uses a Blink app shown on the smartphone's display to shine red and green beams of light at a user's eyes.

The users line up these beams with a dial and the app figures out their refractive error by measuring the difference between where the beams are on the screen and how much they adjust them.
Another device also uses a smartphone to act as a lensmeter, which measures the prescription strength of a user's existing glasses.
To do this, a smartphone running the app is placed in the device, eyeglasses are slid between the phone and the device, and a picture is taken of a pattern beneath the eyeglass lens with the phone's camera.

A third device acts as a phoropter, which helps determine the specific strength of the lens prescription the users need by letting them try different lenses and settings while looking at an eye chart.