Simulating visual acuity. The purpose of this page is to give an idea of how blurry your vision is when you don't use your glasses or contact lenses, or when you use a prescription which doesn't match your eyes. This is illustrated by simulating the blurry perception of a Snellen eye chart, which is commonly used to make eye examinations.
A SCAI answered. Fasting for 9 to 12 hours before a cholesterol blood test ensures accuracy in the test. It helps make sure your body does not have extra sources of fat - say, from the ice cream you had for dessert - that could alter the test results.
Quick Answer. Patients should fast for at least 12 hours before they have a fasting blood test, according to St. John Providence Health System. Not all blood tests require patients to fast, but those that do require that patients abstain from food or any type of beverage besides water before their test. Continue Reading.