LASIK, a common vision correction procedure, often raises questions about its effects beyond improving sight, particularly whether it can change eye color. This article clarifies that LASIK does not alter eye color, explaining why based on the biology of eye color and the LASIK mechanism.
The Science of Eye Color
Human eye color is determined by the amount and type of melanin pigment within the iris, and how light scatters within the iris’s stroma. The iris is the colored part of the eye, a thin, circular structure that controls the size of the pupil. Melanin, the pigment responsible for skin and hair color, is present in two forms: eumelanin (brown hues) and pheomelanin (amber, green, or hazel shades).
The concentration and distribution of these melanin types within the iris dictate the eye’s final color. Brown eyes have a high melanin concentration, while blue eyes have very low eumelanin levels. The appearance of blue, green, and hazel eyes also involves Tyndall scattering, where shorter light wavelengths are scattered more by the stroma, similar to how the sky appears blue. Eye color is an inherited trait influenced by multiple genes.
How LASIK Works
LASIK, or Laser-Assisted In Situ Keratomileusis, is a surgical procedure designed to correct refractive errors like nearsightedness, farsightedness, and astigmatism. This procedure involves reshaping the cornea, the clear, dome-shaped outer surface at the front of the eye. During surgery, an ophthalmologist creates a thin, hinged flap on the cornea’s surface using a femtosecond laser.
Once the flap is lifted, an excimer laser removes small amounts of tissue from the underlying corneal stroma. This reshaping alters the cornea’s curvature, improving its ability to focus light onto the retina. After laser treatment, the corneal flap is repositioned, where it naturally adheres without stitches. The entire procedure is quick, taking only 10 to 15 minutes per eye.
Why LASIK Does Not Change Eye Color
LASIK surgery does not change eye color because it targets only the cornea. The cornea is the transparent outer layer of the eye, functioning like a clear window that focuses incoming light. Eye color is determined by melanin pigment within the iris, which lies behind the cornea.
The excimer laser used in LASIK operates exclusively on corneal tissue, altering its curvature to correct vision problems. The laser energy does not reach or interact with the iris, leaving its natural pigmentation unaffected. Therefore, LASIK has no impact on the melanin in the iris, meaning it cannot alter a person’s natural eye color. Any perceived change in eye color after LASIK is not a direct result of the procedure, and a sudden, actual change in iris color could indicate other ocular health concerns that warrant medical attention.