Corneal Thickness: Why It Matters in LASIK

When exploring the option of LASIK surgery for vision correction, most people focus on the benefits—clear vision without glasses or contact lenses, fast recovery, and lasting results. However, behind the scenes, several critical factors determine whether someone is a good candidate for LASIK. One of the most important, yet often overlooked, is corneal thickness (pachymetry).

What Is the Cornea?

The cornea is the clear, dome-shaped surface that covers the front of the eye. It plays a vital role in focusing light on the retina, much like a camera lens. LASIK works by reshaping the cornea using a laser to correct refractive errors such as nearsightedness (myopia), farsightedness (hyperopia), and astigmatism.

Why Does Corneal Thickness Matter?

LASIK involves creating a thin flap on the surface of the cornea and then using a laser to remove microscopic layers of corneal tissue beneath that flap to change the eye’s focusing power. To do this safely, the surgeon needs a sufficient amount of corneal tissue. Creating a flap changes the structural integrity of the cornea. If the surgeon removes too much tissue or the cornea is naturally too thin, it can compromise the eye’s structural integrity.

The average corneal thickness is around 540 to 550 microns. During LASIK, about 100-160 microns are used to create the flap, and additional tissue is removed depending on the degree of correction needed. Surgeons typically want to leave at least 250 microns of untouched cornea behind to maintain its strength and prevent complications.

The Risks of Thin Corneas

Patients with thinner-than-average corneas are at a higher risk for post-surgical complications, particularly corneal ectasia. This is a condition where the cornea becomes unstable and bulges outward, leading to distorted vision and potentially requiring a corneal transplant in severe cases.

Because of this, corneal thickness is one of the first things evaluated during a LASIK consultation. If a patient’s corneas are too thin, LASIK may not be a safe option.

Alternatives to LASIK for Thin Corneas

Fortunately, thin corneas don’t automatically rule out vision correction surgery. Alternatives like PRK (Photorefractive Keratectomy) and/or lens based surgical options like Implantable Collamer lenses (ICLs) or Refractive Lens Exchange (RLE).

• PRK removes the outer layer of the cornea (epithelium), which regenerates naturally and is about half the size of what the LASIK flap is, and does not involve creating a flap. This allows the surgeon to preserve more of the corneal structure.
• ICL surgery, or Implantable Collamer Lens surgery, is a vision correction procedure where a synthetic lens is implanted inside the eye, between the iris and the natural lens, to correct refractive errors like nearsightedness, farsightedness, and astigmatism. Unlike LASIK, ICL surgery does not reshape the cornea and is reversible. It’s often recommended for patients who have thin corneas or dry eyes and are not suitable candidates for laser eye surgery.
• RLE, also known as clear lens exchange (CLE), is a surgical procedure where the eye’s natural lens is removed and replaced with an artificial intraocular lens (IOL) to correct refractive errors like nearsightedness, farsightedness, or presbyopia. It’s similar to cataract surgery but performed primarily to reduce dependence on glasses or contact lenses, especially in people over 40 who are not ideal candidates for LASIK or other corneal refractive surgeries.

Measuring Corneal Thickness

To assess your suitability for LASIK, eye doctors use a test called pachymetry to measure corneal thickness. This test is quick, painless, and provides highly accurate results. Alongside other diagnostics like corneal topography and wavefront analysis, pachymetry helps your surgeon determine the safest and most effective treatment plan for your eyes.

Final Thoughts

Understanding corneal thickness is essential in determining LASIK eligibility and ensuring safe outcomes. While LASIK offers life-changing benefits for many, it’s not a one-size-fits-all solution. Dishler Laser Institute educates you and helps determine if surgery is truly the right choice for your vision needs. Fortunately, advancements in refractive surgery mean that even patients with thin corneas can explore alternative procedures with confidence.

Considering LASIK or vision correction? Schedule your free consultation online anytime or call our office to get started. Knowing your corneal thickness could be the key to protecting your vision for years to come.