Calibrating a Tablet for Near Vision Testing

Before using a tablet for near vision testing, it must be calibrated to ensure that the test stimuli are correctly sized.

To calibrate a tablet, select the Near chart tab from the Program Options window then click on Show size calibration screen.

This will display the calibration screen shown below on the tablet.

Using a ruler, measure the height of the letter “E”, the box height and the height of the vertical line and width of the horizontal line.  Enter these measurements into the corresponding boxes on the Program Options window along with the proposed viewing distance.  These measurements determine the actual size of the test stimuli displayed on the tablet and it is vital that the measurements are correct.