Eye chart number). The denominator indicates the distance in feet at which a person with normal vision could stand to correctly identify the same symbols identified by the person tested. For example, a visual acuity of 20/20 is considered normal. Numerous types of eye charts exist and are used in various situations. For example, the Snellen chart is designed for use at 6 meters or 20 feet, and is thus appropriate for testing distance vision. There is often also a need to test a subject's vision at near or occupational tasks (such as reading or computer use). For these situations, a Rosenbaum
The Eye of the Giant is forced to admit the truth, but Grover refuses to abandon his expedition on the word of people who claim to have travelled through Time. In order to prove his story, the Doctor suggests that Mike show Grover the “statue” in the pit, which the Doctor believes is in fact a dead alien in a life support suit. Upon arriving at the pit, the Doctor studies the statue for himself and finds a storage unit containing two Semquess drug vials and one empty space; he concludes that the third vial must have broken open in the past, releasing chemicals which