Myopia, commonly known as nearsightedness, is a refractive error where distant objects appear blurry while close objects remain clear. This condition occurs because the eyeball has grown too long, or the cornea, the clear front surface of the eye, is too steeply curved. Either scenario causes light entering the eye to focus at a point in front of the retina rather than directly onto its surface. The goal of any myopia correction method is to shift this focal point backward so that the image lands precisely on the retina, restoring clear distance vision.
Standard Optical Correction
Standard optical correction involves placing an external lens in front of the eye to refract incoming light rays. Eyeglasses and contact lenses utilize a concave, or minus-powered, lens that diverges light before it enters the eye, effectively moving the focal point back onto the retina. Eyeglasses are simple, require minimal maintenance, and can be used at any age, making them a straightforward and cost-effective choice.
Contact lenses, which sit directly on the eye’s surface, offer a wider, more natural field of view and eliminate the peripheral distortions that can occur with glasses. They are often preferred for active lifestyles and sports because they do not fog up or get in the way of activity. The two main types of contacts are soft lenses, made from flexible, water-containing plastic for immediate comfort, and rigid gas permeable (RGP) lenses. RGP lenses are smaller, more durable, and sometimes provide sharper vision for higher prescriptions, though they require a longer adaptation period.
For eyeglasses, single vision lenses correct vision for only one distance, typically far away for myopic individuals. If presbyopia, the age-related loss of near focusing ability, also develops, the patient may need a second pair of reading glasses or switch to progressive lenses. Progressive lenses offer a seamless transition of power from distance vision at the top to near vision at the bottom, all within a single lens, without the visible line found in older bifocals.
Non-Surgical Corneal Reshaping
Orthokeratology (Ortho-K) is a non-surgical method that uses specialized contact lenses to temporarily reshape the cornea while the patient sleeps. These custom-fitted, RGP lenses apply gentle pressure to the central cornea, causing it to flatten slightly during the night. When the lenses are removed in the morning, the cornea retains its new, flatter shape, allowing light to focus correctly on the retina throughout the day, providing clear vision without glasses or daytime contacts.
The effect is temporary and reversible; the cornea reverts to its original shape if the lenses are not worn consistently. Ortho-K is most effective for individuals with mild to moderate myopia, typically up to -6.00 diopters. The treatment is also frequently used in children and adolescents because it has been shown to slow down the progression of myopia by controlling the eye’s axial elongation.
Permanent Vision Correction Surgery
Laser refractive surgery procedures alter the shape of the cornea to permanently fix the focus error. The most common procedure is LASIK (Laser-Assisted In Situ Keratomileusis), which begins by creating a thin, hinged flap on the cornea using a femtosecond laser. The flap is then lifted, and an excimer laser reshapes the underlying stroma before the flap is put back into place. This method is favored for its rapid visual recovery, with many patients experiencing significantly improved vision within 24 hours.
Photorefractive Keratectomy (PRK) is a surface ablation technique that does not involve creating a corneal flap. Instead, the cornea’s outermost layer, the epithelium, is completely removed before the excimer laser reshapes the underlying stroma. Because the epithelium must regenerate over the treated area, the recovery time for PRK is longer and involves more initial discomfort than LASIK, often taking several days to weeks for vision to stabilize. PRK is often recommended for patients with thin corneas or those involved in contact sports, as it eliminates the risk of a flap-related complication from trauma.
SMILE (Small Incision Lenticule Extraction) is a minimally invasive option that uses a femtosecond laser to create a small, lens-shaped lenticule inside the intact cornea. The surgeon then removes this lenticule through a tiny incision, thereby changing the cornea’s shape without needing a large flap. The smaller incision may lead to fewer post-operative dry eye symptoms and better corneal stability compared to LASIK. SMILE is approved for treating certain ranges of myopia and astigmatism, offering a middle ground between the fast recovery of LASIK and the flap-free safety of PRK.
Factors Influencing Treatment Choice
Choosing among correction options requires careful consultation with an eye care professional. Lifestyle is a major consideration; athletes or those with occupations involving potential eye trauma may be better suited for PRK or Ortho-K rather than LASIK. The severity of the myopia also plays a role, as certain treatments like Ortho-K and SMILE are only effective within specific prescription ranges.
Physical characteristics of the eye are significant factors, particularly corneal thickness, which determines eligibility for laser surgeries. Patients must have a stable prescription for a period of time, usually a year, to be candidates for permanent surgical correction. Age is relevant, as myopia progression tends to stabilize in early adulthood, and the use of Ortho-K is often favored for younger patients to help manage the worsening of their vision. Tolerance for risk, commitment to post-operative care, and overall cost also factor into the final choice.