Cover Test

The simulation of the cover test is based on the "Interpolation for Real-Time Assessment", so before using the cover test you have to activate the interpolation for real-time assessment. If you access the cover test via the "General Functions" toolbar, the interpolation for the real-time assessment is automatically activated. When deactivating the cover test, the interpolation is also switched off again. All properties described for the interpolation for real-time assessment can be applied to the cover test as well. The medical background of the cover test can be found in the chapter "Cover Test".

After activating the cover test and after the calculation of the interpolation is finished, a three-dimensional red cover is displayed in the 3D-view. Now you can left-click on this cover and when you move the mouse while keeping the mouse button pressed, you can cover one of the two eyes. If a pathological situation exists, a movement of the eye to pick up fixation can be observed after one eye was covered/uncovered depending on the current settings of the cover test. To modify the settings of the cover test, you can use the menu, which can be accessed with a left-click on the arrow next to the symbol for the activation of the cover test.

In this menu you can configure the following settings:

•Preferred Fixing Eye - specifies the eye, which the "virtual patient" prefers to use for the fixation (after the cover from one eye was removed or if no eye is covered). If the left or the right eye is chosen, the patient always fixates with the selected eye until it is covered.

When using the setting "Both Eyes" the "virtual patient" always fixates with the eye, which was uncovered at last.

•Strabismus Type - specifies the strabismus type. If "Manifest" is selected, then the full squint angle is visible in the 3D-view independently of the position of the cover. If the strabismus type "Latent" is chosen, a part of or the whole squint angle is compensated in a certain gaze position depending on the current motor fusional ability. If you now change the motor fusional ability, the change is shown in the 3D-view immediately.

•Transparent Cover - by default the cover is drawn in a semi-transparent way, so that the covered eye and its movement to pick up fixation during the covering are visible. With this function you can switch off the transparency of the cover.

If you select a preferred fixing eye or if one of the two eyes is covered, you cannot switch the fixation as long as the cover test is active or one of the eyes is covered!