How Is LASIK Surgery Performed?

LASIK is a refractive surgery procedure that uses a laser to change the curvature of the cornea (the clear tissue on the surface of your eye) by removing or ablating corneal tissue. Reshaping the cornea corrects common vision errors including nearsightedness (myopia), farsightedness (hyperopia), and astigmatism.

During LASIK surgery, a flap of 100-120 microns (μm) in thickness is created and then lifted. Your refractive surgeon then uses a laser to ablate microscopic amounts of corneal tissue until the desired shape is reached to correct your vision. The higher the correction, the more corneal tissue needs to be removed.

Why Might I Not Be a Candidate for LASIK Surgery?

The most important LASIK candidacy factors include:

• Healthy eyes

• Age

• If you are currently pregnant or nursing

• The thickness of your cornea

• Refractive error (glasses/contacts prescription)

• Past medical history
  
  

Any preexisting eye conditions must be addressed before undergoing LASIK surgery. Generally, healthy eyes without severe symptoms of dryness make you a good candidate for LASIK. You must be at least 18 years old with a stable prescription that has not changed in the last two to three years. Age-related presbyopia (farsightedness) for people over 40 years old cannot be corrected by LASIK. A high refractive error may disqualify you for LASIK. It is not recommended for people who are currently pregnant or nursing to have LASIK surgery. Consult with your ophthalmologist whether or not your past medical history may disqualify you for LASIK surgery.

Corneal Thickness

Because corneal tissue is ablated during LASIK surgery, there is a minimum threshold of corneal thickness needed to remain after LASIK to ensure the safety and stability of a patient’s cornea over time. There must also be enough corneal tissue in place to be reshaped. At Coastal Vision Medical Group, we follow the recommendations from the American Academy of Ophthalmology. In a recent publication by Buckner, MD et. al (May 2020), a corneal thickness of about 300 μm was recommended to remain after ablating and before the flap is repositioned.

You may not be a candidate for LASIK surgery if you have thin corneas. Thin corneas can make LASIK surgery riskier, potentially leading to serious complications over time. The cornea may not be able to maintain its shape and curvature resulting in a rare complication called corneal ectasia. Post-LASIK corneal ectasia resembles keratoconus where the cornea bulges outward into a cone shape. For patients with a higher preoperative prescription, corneal thickness plays a larger role since more tissue must be ablated to achieve vision correction.

It is important to work with your surgeon to address corneal thickness before LASIK surgery to identify if you are a good candidate for LASIK. Corneal thinning can lead to distorted vision. At Coastal Vision, we provide comprehensive corneal imaging to determine if a patient is a good candidate for LASIK. Our ophthalmologists use advanced imaging technology to assess a patient’s corneal topography, and preoperative corneal thickness is weighed with other factors including the patient’s age, medical history, and prescription strength. Oftentimes, multiple machines are used to assess different aspects of the corneal thickness, shapes, asymmetry, and tear film quality.
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What Are My Options if I am Not a Candidate for LASIK Surgery?

If you are not a good candidate for LASIK, there are other options available. PRK or photorefractive keratectomy is a type of refractive surgery that uses a laser (the same laser used in LASIK) to change the shape of the cornea without creating a flap. It is a great alternative for patients with thin corneas and low correctional value.

Another alternative is an implantable Collamer lens (ICL). ICL acts similarly to contact lenses, except instead of placing them on top of the eye, ICL is surgically positioned inside the eye between the iris and natural lens of the eye. Collamer lenses are highly biocompatible with the eye and have been used successfully inside the eyes for a few decades. ICL remains in the eye permanently, providing exceptional quality of vision. Collamer lenses are a great alternative for myopic (nearsighted) patients with thin corneas and/or a high degree of myopia (nearsightedness) with or without astigmatism.

Lastly, some patients might benefit from refractive lens exchange (RLE). This procedure is typically chosen for patients with early stages of cataract, high degrees of hyperopia (farsightedness), and/or to manage age-related presbyopia (farsightedness) for patients older than 40 years old. In this procedure, the natural lens is removed and replaced with an intraocular lens (IOL). There are many IOL options, depending on your visual needs and lifestyle. Your refractive surgeon will discuss your IOL options with you if RLE is the chosen procedure.

Coastal Vision Medical Group is here for you when you are ready to discuss your options. Call (888) 501-4496 to book an appointment at any of our four locations or use our online contact form.