Laser-Assisted in Situ Keratomileusis (LASIK) reshapes the cornea, the eye’s front surface, to correct refractive errors and reduce the need for glasses or contact lenses. A cataract is a clouding of the eye’s natural lens, which sits behind the iris and pupil. Many people who had LASIK wonder if the surgery increases their risk of developing this common age-related condition later in life. Understanding the distinct anatomical locations and mechanisms of these two eye conditions clarifies why LASIK does not cause cataracts.
How LASIK Affects the Eye
LASIK is a form of refractive surgery that permanently alters the curvature of the cornea, the clear, dome-shaped tissue at the front of the eye. The procedure involves creating a thin, hinged flap on the surface using a microkeratome or a femtosecond laser. Once lifted, an excimer laser precisely removes tissue from the underlying corneal bed, changing its shape to correct refractive errors. This procedure focuses only on the front layer of the eye, which provides about two-thirds of the eye’s total focusing power. The laser used in LASIK does not penetrate the cornea to reach the natural lens, which is located deep inside the eye. Therefore, LASIK does not physically interact with or damage the lens tissue, establishing the anatomical reason why the surgery cannot cause a cataract.
Cataracts Happen Regardless of LASIK
Cataracts are an almost universal part of the human aging process, developing independently of whether a person has had previous eye surgery like LASIK. The natural lens is composed of water and proteins arranged in an orderly structure to keep the lens clear. Over a person’s lifetime, these lens proteins break down and clump together, causing the lens to become cloudy or opaque. This clouding typically affects vision around age 60 or later. Since LASIK is performed on younger adults, the eventual development of a cataract decades later is simply the expected progression of natural biological aging. Having had LASIK neither accelerates nor prevents the degradation of lens proteins that leads to cataract formation.
Measuring the Eye After LASIK
The primary challenge for post-LASIK patients who develop cataracts is accurately calculating the power for the new intraocular lens (IOL) implant. Standard IOL calculation formulas rely on measuring the cornea’s curvature (keratometry) and assume a normal relationship between the front and back surfaces. LASIK permanently alters the anterior (front) corneal surface curvature but does not change the posterior (back) surface. Traditional measuring devices and formulas are often inaccurate in this altered eye, leading to a miscalculation of the eye’s true focusing power. For example, after myopic LASIK, standard measurements tend to overestimate corneal power, which can lead the surgeon to select an IOL that is too weak, resulting in a farsighted outcome. The difficulty is compounded if the patient’s original pre-LASIK records are unavailable decades later. To address this, surgeons use specialized formulas, such as the Barrett True-K or Haigis-L, designed to account for post-refractive surgery changes. Advanced diagnostic tools, including optical biometers and corneal topographers, measure the total corneal power more precisely. Surgeons may also use intraoperative aberrometry, which measures the eye’s refractive error during the surgery, providing a final check on the IOL power before implantation.
Cataract Surgery in the Post-LASIK Eye
The removal of the cloudy natural lens during cataract surgery uses the standard technique of phacoemulsification, which involves breaking up the lens with ultrasound and suctioning it out. Surgeons must exercise caution during the initial stages. A small incision is typically made at the edge of the cornea to access the eye’s interior. In a post-LASIK eye, the surgeon must carefully plan the incision location to avoid catching the edge of the old LASIK flap, which could lead to dislocation or tearing. The surgical technique itself is not dramatically different, but the unique planning centers on selecting the appropriate IOL, complicated by the altered corneal shape. Patients who had LASIK often expect spectacle independence, and specialized IOLs like multifocal or toric lenses may be considered. However, subtle corneal irregularities or aberrations from the prior LASIK can sometimes make advanced lens designs less effective than in an eye without previous refractive surgery.