What is Myopia?
More than 70 million people in North America (about one in four) are myopic (nearsighted). The term “nearsighted” means that you can see objects that are closer to you more clearly than distant objects. The more myopic you are the more blurred distant objects appear. If you have a highly myopic prescription, you are likely to have very thick edges to your glasses.
Clear vision is dependent on light rays converging precisely on the retina, a light-sensitive membrane at the back of the eye. The optical system of a normal eye, comprising the cornea, crystalline lens, and vitreous body, orchestrates this precise convergence, ensuring that objects are projected sharply onto the retina. This intricate process of light ray redirection is known as refraction. The total refraction of the eye is measured in diopters (D), representing the optical power of the cornea, lens, and vitreous body. When the total refractive power of the eye is zero diopters, objects are focused flawlessly on the retina, resulting in sharp, undistorted vision.
Nearsightedness, also known as myopia, typically stems from an elongated eyeball, causing the light rays to converge too soon, in front of the retina instead of directly upon it. This refractive error results in blurred vision for distant objects. The severity of nearsightedness determines the distance at which objects appear clear. Individuals with severe myopia may only perceive distant objects clearly up to a few inches away, while those with mild myopia may be able to focus on and see distant objects clearly from several yards. Optical correction for nearsightedness aims to reduce the overall refractive power of the eye, effectively shifting the focal point back onto the retina.