Contrast Vision

This medical test is to measure disturbed visual function in addition to classical visual acuity. Large test figures and variable contrast allow an examiner to quantify visual function when vision is strongly reduced and the classical acuity tests at a distance are not effective.
The visual acuity is tested by showing a subject randomly oriented Snellen E’s with decreasing contrast and decreasing size until the subject is no longer able to recognize figures. The examiner presses a button according to the answer of the subject. Five different answers are possible (up, down, left, right, unknown).
The test results are displayed on a chart where they can be compared to normal values. The chart (jpg file) and the measured values (.csv file) can both be exported by email.

How to use this test :
Enter the name of the patient, then start a new test.
There are two different test distances:

Test distance 120 cm: This test is applied for average to good visual acuity and will show a progressive reduction of contrast sensitivity at high visual acuity. Changes in contrast sensitivity can occur due to cataract, glaucoma, diabetic retinopathy or after LASIK, PRK and other types of refractive surgery.

Test distance 30 cm: At close distance the large size of the E's allows visual function to be tested even if the acuity is reduced. Contrast measurements result in a quantitative assessment even in cases with low visual acuity, down to an acuity of 0.004 (20/4400). Changes in visual function in age related maculopathy (AMD) can be followed during anti-vascular endothelial growth factor (anti-VEGF) medication.

Medical advisor: Prof. Christophe Huber, Zürich


**this app is for use with a regular size iPad (retina or non-retina); it has not been calibrated for the iPad mini**