Refractive Errors: What you Should Know
Living with poor vision? You’re not alone. Millions of people across the world have refractive errors like myopia, hyperopia, astigmatism and presbyopia. Keep reading to learn more about these conditions and how each one affects your eyesight.
Myopia, also known as nearsightedness, affects roughly 30% of Canadians, according to Doctors of Optometry Canada. This condition prevents the eye from focusing on far away objects. Myopia is caused when the rays of light that are supposed to focus on the surface of the retina only reach the front part of the eye. This is often the result of the cornea’s shape: Either it is too curved or the eyeball is too long.
Hyperopia, or farsightedness, means that the eyes are unable to focus on images that are near because the cornea is not curved enough, or the eyeball is not long enough. With hyperopia, it becomes difficult to see an object clearly from a near distance. The eye must therefore strain in order to focus on near objects, more than it would for objects at a far distance.
Round eyes are ideal for perfect vision, but this is rare. This is why many people develop astigmatism to some degree. Astigmatism happens when the lens or cornea is misshapen and takes on an ovular or cylindrical shape. Because of this, light cannot focus on the retina, so eyesight from any distance becomes contorted and blurry.
Vision changes with age. This is sometimes the result of a refractive error, such as presbyopia, which can affect people as early as their 40s. The ability to see objects at a near distance diminishes due to a lack of flexibility in the eye’s crystalline lens, which is located behind the coloured iris.