Mesoamerican ballgame many Caribbean islands including Cuba, Puerto Rico, and the West Indies, has been proposed as a descendent of the Mesoamerican ballgame, perhaps through the Maya. Mesoamerican ballgame The Mesoamerican ballgame was a sport with ritual associations played since 1400 BC by the pre-Columbian people of Ancient Mesoamerica. The sport had different versions in different places during the millennia, and a newer more modern version of the game, "ulama", is still played in a few places by the indigenous population. The rules of the game are not known, but judging from its descendant, ulama, they were probably similar to racquetball, where
Fixation disparity Fixation disparity Fixation disparity exists when there is a small misalignment of the eyes when viewing with binocular vision. The misaligment may be vertical, horizontal or both. The misalignment (a few minutes of arc) is much smaller than that of strabismus, which prevents binocular vision, although it may reduce a patient's level of stereopsis. A patient may or may not have fixation disparity and a patient may have a different fixation disparity at distance than near. There are several methods to quantify fixation disparity. The Mallett card, the Bernell lantern slide, the Wesson Card and the Disparometer may be used.