How to measure your vision in the OKKO Health Adults App, and what each of the tests measures.

1: Contrast Sensitivity

The first test in the OKKO Health app measures your contrast sensitivity. Dots in different shades of grey will appear in waves on the screen, and the aim is to tap the ones you can see. 


Some dots are more difficult to see than others. The purpose of this is to carefully test your ability to see different levels of contrast.

To keep the test relevant and personal to each user, the dots will gradually become harder and harder to see, as a way to find the user's limit. But if the user is found to struggle, the dots once again become more visible.

Higher contrast sensitivity scores indicate better performance

2: Acuity

The second test measures something called ‘Near Visual Acuity’. This is a similar test to the more traditional eye chart, typically used when visiting an optician. But instead of looking at letters, we want you to look for vanishing optotypes - we call these 'OKKO Circles'.


Circles in various sizes will appear on the screen, and the aim is for you to tap all the circles you can see. The smaller the circle gets, the harder they are to see.

Following a similar path to the first test, the app will tailor the circles to your vision.

Acuity is measured in something called 'LogMAR'. The lower the LogMAR score, the better the performance. 

3: Hyperacuity

The third test measures your ability to see minor misalignment. This test is particularly looking for the degree of distortion/blind spots within the user's vision. 


Dots in a circle appears on the screen, one of which is slightly misaligned. The aim is for the user to tap the dot that they think is outside of the circle. The misalignment gets less noticeable as the test goes on, making it more difficult to identify. If the user is struggling, the dot will move further out of the circle.

Following a similar path to the previous two tests, the app will tailor the misalignment to your vision.

Hyperacuity is measured in reaction time.