Laser surgery can effectively correct astigmatism, offering clearer vision without the constant need for glasses or contact lenses. This common eye condition, characterized by an irregular eye shape, can significantly impact daily life by causing blurred or distorted vision. Modern laser procedures precisely reshape the eye’s surface, allowing light to focus properly. This article explores how laser surgery addresses astigmatism, detailing the procedures involved, patient suitability, and expected outcomes.
Understanding Astigmatism
Astigmatism arises from an imperfection in the curvature of the eye’s cornea. Normally, the cornea and lens are uniformly rounded, similar to a basketball, allowing light to focus sharply on a single point on the retina. With astigmatism, however, the eye’s surface is shaped more like a football or a rugby ball, with different curvatures in different directions. This irregular shape causes light rays entering the eye to bend unevenly, preventing them from focusing correctly on the retina and resulting in blurred or distorted vision at all distances. Astigmatism often occurs alongside nearsightedness or farsightedness.
The Mechanism of Laser Correction
Laser surgery corrects astigmatism by precisely reshaping the cornea. This reshaping procedure, known as photoablation, involves the controlled removal of corneal tissue using a specialized laser. By altering the cornea’s curvature, the laser enables light to bend uniformly as it enters the eye. This allows the light to focus accurately on a single point on the retina, improving visual clarity. The goal is to transform the eye’s irregular, rugby ball-like shape into a more spherical form, similar to a soccer ball.
Primary Laser Surgery Options
Several laser eye surgery options correct astigmatism. The most common is LASIK (Laser-Assisted In Situ Keratomileusis), where a thin, hinged flap of tissue is created on the cornea’s surface. This flap is lifted to expose the underlying corneal tissue, which an excimer laser then reshapes to correct the astigmatism. After reshaping, the flap is repositioned, adhering without stitches and healing. LASIK is known for its rapid visual recovery, with patients experiencing improved vision within 24 hours.
Another option is Photorefractive Keratectomy (PRK), which differs from LASIK by not creating a corneal flap. Instead, the surgeon removes the outer layer of the cornea, called the epithelium, before using an excimer laser to reshape the underlying corneal tissue. The epithelium then regenerates over several days. PRK can be a suitable choice for individuals with thinner corneas or those who may not be ideal LASIK candidates due to certain corneal conditions. However, the recovery period for PRK is longer, and patients may experience more discomfort initially compared to LASIK.
A newer procedure, Small Incision Lenticule Extraction (SMILE), offers a minimally invasive approach to correcting astigmatism and nearsightedness. During SMILE, a femtosecond laser creates a small, lens-shaped piece of tissue, known as a lenticule, inside the intact cornea. This lenticule is then removed through a tiny incision. By removing this piece of tissue, the cornea’s shape is changed, correcting the refractive error. SMILE is considered a flap-free technique, which may lead to reduced instances of postoperative dry eyes and greater corneal stability compared to LASIK.
Candidate Assessment and Surgical Process
Determining suitability for laser eye surgery involves a comprehensive assessment. Candidates need to be at least 18 years old, with stable vision that has not changed for at least one year. Overall eye health is important, including the absence of eye diseases, infections, or conditions such as severe dry eye or keratoconus. The thickness and shape of the cornea are evaluated, as the procedure involves removing small amounts of corneal tissue.
The surgical process begins with an eye examination and consultation, where the surgeon measures the eye and discusses the procedure’s benefits and considerations. On the day of the surgery, numbing eye drops are administered. An eyelid holder is used to prevent blinking, and the procedure itself is quick, often taking only a few minutes per eye. Patients are awake but relaxed during the procedure and are asked to focus on a target light while the laser reshapes the cornea.
Post-Surgery Outcomes and Considerations
Following laser surgery for astigmatism, patients experience improved vision, often reducing or eliminating their reliance on glasses or contact lenses. Success rates for LASIK are high, with over 90% of patients achieving 20/20 vision or better, and over 98% achieving their visual goals. Most patients report satisfaction with the results.
While vision improvement is often rapid, full stabilization can take several weeks to months. Temporary side effects are common during the recovery period, including dry eyes, which can last for a few months. Some individuals may also experience visual disturbances such as glare, halos around lights, or light sensitivity, especially at night. These effects subside as the eyes heal.
In some instances, residual astigmatism may occur, or the initial correction might be an undercorrection or overcorrection, occasionally necessitating an enhancement procedure. Following all post-operative instructions, including using prescribed eye drops and attending follow-up appointments, is important for healing and long-term eye health.