Top selling diagnostic and therapeutic app for iPad, iPhone and iPod Touch! OKN Strips can be used to elicit Optokinetic Nystagmus (OKN) for evaluation of neurological, otological or opthalmological disorders, includes a Red Desaturation mode and now has an Amsler grid for additional eye testing. OKN Strips: Tap the screen to cycle through speeds of the moving strips. Tap the strips icon in the bottom toolbar to toggle the color of the strips between Red and Black. Pinch or Zoom with two fingers to change the width of the strips. Swipe against the direction the strips are moving to reverse their direction. Tap the screen with two fingers to hide or show the bottom toolbar. On the right side of the bottom toolbar there's icons to open the Red Desaturation and Amsler Grid. Red Desaturation: Use the colored circle to perform a red desaturation test. Amsler Grid: Use the Amsler grid to perform eye tests. The buttons on the bottom toolbar change color combinations of the grid.