The Netrometer is a companion app for a Samsung S4-based lensometer. You can see more information and buy the device here: https://eyenetra.com/product-netrometer.html
The Netrometer measures the refractive power of eyeglasses. The smartphone camera captures a picture through single vision or progressive lenses and the app computes the refractive data in seconds. With the precision of 0.08D, the Netrometer is as accurate as top-tier lensometers used in the clinics.
The Netrometer app connects the device results to the Insight platform: an on-line, HIPAA-compliant EMR. Insight provides all the necessary tools to allow eye care providers to perform refractions anywhere.