Mesoamerican Long Count calendar number (portion of the DN preceding era date) 7.2.14.19<br> Add Ring number to the ring number date to reach 13.0.0.0.0 Thompson contains a table of typical long reckonings after Satterwaite. The "Serpent Numbers" in the Dresden codex pp. 61–69 is a table of dates using a base date of 1.18.1.8.0.16 in the prior era (5,482,096 days). Mesoamerican Long Count calendar The Mesoamerican Long Count calendar is a non-repeating, vigesimal (base-20) and base-18 calendar used by several pre-Columbian Mesoamerican cultures, most notably the Maya. For this reason, it is often known as the Maya (or Mayan) Long Count calendar. Using a
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.