In order for the eyes to function properly light has to be refracted, or bent, by the cornea and the lens. A refractive error is considered to be a defect in the shape of your eye because it does not bend light correctly which can cause vision problems. When this happens patients see blurred or fizzy images. There are four types of refractive errors: myopia (nearsightedness), hyperopia (farsightedness), astigmatism (blurred vision on objects that are both near and far) and prebyopia (difficultly focusing on nearby objects). A patient can have any combination of these errors with their vision and can change overtime. Normal vision, with only small errors, is measured at 20/20 meaning that this person is able to see objects that are 20 feet away the way others would see it at that distance. The measurement goes up when it is more difficult to see, for example if someone had 20/80 vision, they have to see the object at 20 feet to be able to see what normal vision sees at 80 feet. Refractive errors are commonly treated using either glasses or contacts, depending on the patient’s preference, allowing for ideal vision. Surgeries have also become increasingly popular with a procedure called Lasik; most surgical techniques will either change the curvature of the cornea or use an artificial lens to correct vision.