LASIK and Phakic IOLs: Myopia Correction Explained - Ophthalmology

More Info

---

LASIK (Laser-Assisted In Situ Keratomileusis) and Phakic Intraocular Lenses (IOLs) are two popular methods for correcting myopia (nearsightedness), each with its own mechanisms and considerations. Understanding how these procedures work can help clarify your questions about corneal reshaping, lens implantation, and the relationship between the cornea and the lens.

LASIK Overview:
LASIK is a refractive surgery that involves reshaping the cornea, the clear front part of the eye, to improve vision. During the procedure, a thin flap is created on the cornea using a microkeratome or a femtosecond laser. This flap is then lifted, and an excimer laser is used to remove a precise amount of corneal tissue beneath the flap. The amount of tissue removed depends on the degree of myopia being corrected. After the laser treatment, the flap is repositioned, and it adheres naturally without the need for stitches.

1. Corneal Reshaping: The part of the cornea that is removed during LASIK is primarily the central and mid-peripheral corneal tissue. This reshaping flattens the cornea, which helps to reduce the focusing power of the eye, allowing light to focus more accurately on the retina.

2. Corneal Size: Yes, LASIK does make the cornea slightly smaller in terms of thickness, but it does not significantly change the overall diameter of the cornea. The cornea's curvature is altered to improve vision, but the eye's overall structure remains intact.

3. Lifetime of LASIK: While LASIK can be performed more than once, it is generally recommended to limit the number of procedures due to potential complications and changes in corneal thickness. Most patients achieve satisfactory results with a single LASIK procedure, but some may require enhancements later in life due to changes in vision.

Phakic IOLs Overview:
Phakic IOLs are another option for correcting myopia, particularly for patients who may not be suitable candidates for LASIK due to high levels of myopia or thin corneas. A phakic IOL is an artificial lens that is implanted in the eye without removing the natural lens (the crystalline lens).

1. Implantation Process: The procedure involves making a small incision in the cornea to insert the phakic IOL, which is placed in front of the natural lens. Unlike cataract surgery, where the natural lens is removed, phakic IOLs work alongside the existing lens.

2. Myopia and Lens Relationship: Myopia occurs when the eye is too long or the cornea is too steep, causing light to focus in front of the retina. The crystalline lens can also contribute to refractive errors, but it primarily focuses light onto the retina. The cornea plays a significant role in the eye's overall refractive power, and both structures must work together for optimal vision.

3. Post-LASIK Options: After undergoing LASIK, it is generally not advisable to implant a phakic IOL because the cornea has already been reshaped. However, if a patient experiences significant vision changes or complications after LASIK, they should consult with an ophthalmologist to discuss potential options, which may include other corrective procedures.

In summary, LASIK reshapes the cornea to correct myopia by removing tissue, while phakic IOLs involve implanting a lens without removing the natural lens. Each procedure has its indications, benefits, and limitations. If you are considering either option, it is essential to have a thorough discussion with an eye care professional who can evaluate your specific situation and recommend the best course of action for your vision correction needs.