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Peek Acuity calibration FAQ

These following frequently asked questions (FAQ) refer to calibration for the Peek Acuity and Peek Acuity Pro apps. 

If you have general questions about Peek, please read Peek Vision FAQ, and for questions about Peek Retina, our portable smartphone eye camera, visit Peek Retina FAQ.  Alternatively, please contact us.

Please perform the calibration check for your device.  

If both width and height measurements are correct, you can continue to use Peek Acuity with confidence that the results will be at least accurate as conventional vision charts.

If either or both measurements are not within the specified range (38mm - 42mm), please do not use your device to conduct Peek Acuity vision checks, as the results will be inaccurate.

You may not have the latest version of Peek Acuity installed.  Please update the app via Google Play store (Peek Acuity / Peek Acuity Pro).  You should be prompted to calibrate the app automatically - if not, please refer to the instructions on the Peek Acuity calibration page.

We’re working on a new way to produce accurately sized letters in Android devices which doesn’t rely on pixel density.  We'll update the apps as soon as this is ready, but at the moment we can't say when this will be, as it involves significant development time.


As far as we’re aware, the problem of some Android devices misreporting pixel density hasn’t been identified previously.  Pixel density is a standard method to provide accurate measurements in an app environment, and this problem affects not just the Peek Acuity apps, but other applications which use the same method to produce accurate sizing, such as “ruler” apps.  

No.  To the best of our knowledge, the issue of Android devices misreporting pixel density hasn’t been identified previously.  Because this is a newly-identified problem, it's not known whether every device of a particular make or model is affected.  This is why we've provided a calibration check so that every app user can find out whether their device is functioning correctly.

36 million people worldwide are blind.  Four in five of them could keep their sight with simple surgery or treatment.  Millions more can't see clearly, yet need no more than a simple pair of glasses.  We won't stop until everyone has been linked to the treatment and services they need.