Nearsightedness, also known as myopia, is a common vision condition where distant objects appear blurry while close-up objects remain clear. If you are nearsighted, you may have difficulty seeing things far away, such as road signs or a whiteboard. Myopia is a refractive error, indicating an issue with how the eye focuses light.
Understanding Nearsightedness
Nearsightedness occurs when the eye’s shape causes light to focus improperly. Instead of light rays converging directly on the retina at the back of the eye, they focus in front of it. This misfocus results in distant images appearing indistinct or fuzzy.
The primary anatomical reasons for this light misdirection are an eyeball that is too long from front to back, or a cornea (the clear front surface of the eye) or lens that has too steep a curvature. Both conditions cause light to bend too much, or converge too strongly, before it reaches the retina.
Individuals with nearsightedness commonly experience symptoms like blurry distant vision, needing to squint to see clearly, and eye strain. Headaches can also occur. This condition begins in childhood, often between the ages of 6 and 14, and can worsen during the teenage years as the eye continues to grow. Vision stabilizes by the early twenties, between ages 17 and 21.
Genetic factors play a significant role in the development of nearsightedness, with the risk increasing if one or both parents are nearsighted. Environmental and lifestyle factors also contribute, with increased time spent on close-up activities like reading or using digital screens linked to a higher risk. Spending less time outdoors is also linked to increased nearsightedness.
Correcting Nearsightedness
Correcting nearsightedness primarily involves refocusing light onto the retina. Eyeglasses and contact lenses are the most common methods to achieve this. These corrective lenses use a concave shape, meaning they are thinner in the center and thicker at the edges.
Concave lenses work by diverging the incoming light rays before they enter the eye. This divergence counteracts the eye’s tendency to focus light too soon, allowing the light to land precisely on the retina. The strength of these lenses is measured in diopters, with higher negative numbers indicating a stronger lens needed for greater degrees of myopia.
For more permanent solutions, refractive surgeries like LASIK (laser-assisted in situ keratomileusis) and PRK (photorefractive keratectomy) are available. Both procedures use a laser to precisely reshape the cornea, the eye’s clear front surface. By altering the corneal curvature, these surgeries change how light enters the eye, directing it to focus correctly on the retina.
In LASIK, a thin, hinged flap is created on the cornea’s surface, lifted, and then a laser removes tissue to reshape the underlying cornea before the flap is repositioned. PRK involves removing the outermost layer of corneal cells before the laser reshapes the cornea. These surgical methods aim to reduce or eliminate the need for glasses or contact lenses by permanently adjusting the eye’s focusing power.