due to slow pixel response time. Liquid crystal displays have traditionally been slow to change from one polarization state to another. Users of early 1990s laptops are familiar with the smearing and blurring that occurs when something moves too fast for the LCD to keep up. LCD technology is not usually rated by frames per second but rather the time it takes to transition from one pixel color value to another pixel color value. Normally, a 120 Hz refresh is displayed for a full 1/120 second (8.33 milliseconds) due to sample-and-hold, regardless of how quickly an LCD can complete pixel transitions. Recently, it became possible to hide pixel transitions from being seen, using strobe backlight technology, by turning off the backlight between refreshes, to reduce crosstalk. Newer LCD televisions, including high end Sony and Samsung 3D TVs, now utilize a strobed backlight or scanning backlight to reduce 3D crosstalk during shutter glasses operation. Therapeutic alternating occlusion In vision therapy of amblyopia and of intermittent central suppression, liquid crystal devices have been used for purposes of enhanced occlusion therapy. In this scenario, the amblyopic patient wears electronically programmable liquid crystal glasses or goggles for continuously for several hours during regular everyday activities. Wearing the device encourages or forces the patient to use both eyes alternatingly, similar to eye patching, but rapidly alternating in time. The aim is to circumvent the patient's tendency to suppress the field of view of the weaker eye and to train the patient's capacity for binocular vision. The goggles mostly feature a much slower flicker rate than the more well-known active shutter 3D glasses. See also 3D television Digital 3D Teleview LED TV CrystalEyes References External links Panasonic.com/3d – Overview of Technology of 3D Cinema and LC Shutter Glasses 3D Vision reviewed – Nvidia's 3D Vision explained and reviewed Stereoscopy Liquid crystal displays 3D imaging Eyewear