The eye of a tornado is an area of low barometric pressure at the epicenter, or core, of the tornado’s condensation funnel. An annulus, a circular area known as the eye, is created when the low barometric pressure at the base of the core forces the air at the top downward. Once this air reaches the ground, it mixes with the air rushing in, which begins to spiral upward around the downward rush of air. 
How Big Are These Eyes?
Eye size is dependent upon the storm’s size. While tropical storms have eyes that are very wide, sometimes as many as fifty miles in diameter, tornados are a much more compact phenomenon and their eyes are correspondingly smaller. Often the eye of a tornado is only several feet or yards. 
Is the Eye of a Tornado Windless and Calm?
Theoretically, the eye of any funnel cloud has wind speeds approaching zero miles per hour as you approach the epicenter. Large meteorological storm systems, such as hurricanes, have correspondingly larger eyes. This allows for a sizeable region of low wind speeds and relative calm near the eye’s center. Tornado funnel clouds are not as widespread. The eyes of tornados are therefore much more chaotic than those found in hurricanes or other tropical storms. While wind speeds also theoretically approach zero as you approach a tornado’s center, the funnel clouds are constantly moving, pushed by the interplay of drafts or air pressures. With such a narrow eye, there is often no stable point of perfect calm that a human being can appreciate.
 “Tornado (meteorology) : Violent (EF4 and EF5) Tornadoes.” Encyclopedia Britannica Online. Encyclopedia Britannica, n.d. Web. 23 Jan. 2013. <http://www.britannica.com/EBchecked/topic/599941/tornado/218370/Violent-EF4-and-EF5-tornadoes>.
 “Tornado and Hurricane Eyes.” Tornado and Hurricane Eyes. N.p., n.d. Web. 23 Jan. 2013. <http://www.newton.dep.anl.gov/askasci/wea00/wea00005.htm>.
University of Illinois
National Severe Storms Laboratory: