Myopia, commonly known as nearsightedness, is a widespread vision condition where distant objects appear blurry or hazy. This refractive error affects a significant portion of the global population, making everyday tasks like reading road signs or seeing a blackboard challenging. This article explores the anatomical and visual characteristics of a myopic eye and how modern interventions can improve vision.
The Eye With Myopia
An eye with myopia exhibits specific physical characteristics that prevent light from focusing correctly on the retina. The most common cause is an elongated eyeball, meaning it has grown too long from front to back. In some instances, the cornea, the clear front surface of the eye, might be overly curved. These structural differences cause incoming light rays to converge and focus in front of the retina rather than directly upon it, resulting in a blurred image.
A Myopic View
Individuals with myopia experience a visual world where distant objects lack sharpness. A movie screen or distant road signs may appear indistinct or blurred, even while objects up close, like a book or phone, remain clear. This disparity in clarity often leads to behaviors such as squinting, an attempt to reduce the amount of unfocused light entering the eye and temporarily improve distant vision.
The subjective experience of myopia can range from mild blurriness, where distant details are slightly fuzzy, to severe impairment, where objects just a few feet away are unclear. This condition begins in school-age children and can progress through adolescence, stabilizing around age 20.
Correcting Myopia
Various methods are used to correct myopia, each working to redirect light so it focuses accurately on the retina. Eyeglasses and contact lenses are common non-surgical options that provide clear vision when worn. Refractive surgeries, such as LASIK and PRK, offer more lasting changes to the eye’s structure.
Eyeglasses use concave lenses, which are thinner in the center and thicker at the edges, to diverge light rays before they enter the eye. This divergence compensates for the eye’s excessive focusing power, allowing light to land directly on the retina. Contact lenses achieve a similar effect by sitting directly on the eye’s surface, altering the light’s path to ensure proper focus. LASIK and PRK reshape the cornea to change how light is refracted.
The Transformed Eye
After correction, the eye’s ability to focus light is significantly altered, leading to clear distant vision. With refractive surgeries like LASIK, an excimer laser precisely removes microscopic amounts of tissue from the cornea, flattening its curvature. This reshaping allows light to converge directly on the retina, eliminating the blur previously experienced. The procedure takes about 10 to 15 minutes for both eyes, with many patients noticing immediate visual improvement.
Similarly, PRK reshapes the cornea by removing the outermost layer (epithelium) and then using a laser on the underlying tissue. The epithelium regrows naturally, and the altered corneal shape ensures light focuses correctly.