We have all heard words like nearsighted, farsighted, myopia, hyperopia, hypermetropia, and astigmatism. All of these are terms used to describe different types of ametropia, or refractive error. Optically, refractive error is relatively simple to understand. In an eye with no refractive error, light enters the eye and is refracted (i.e. bent) in such a way that if falls precisely on the retina. The retina is a thin, multilayered structure at the back part of the eye, and its job is to relay the visual information from the eye to the brain.
Myopia, hyperopia, and astigmatism are all common refractive errors that are prevalent worldwide today. Thankfully, they are treatable and modern contacts and glasses can provide both comfort and optical clarity. However, these ametropias are not the only thing that could be the cause of reduced vision. In cases such as amblyopia or a number of pathologies that affect the structures of the eyes, refractive error can be completely corrected, and the patient could still not have crisp, clear vision. So, in addition to an annual eye exam, it is important to note and discuss any vision changes that you may be experiencing with your optometrist.