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Why Is Corneal Thickness Important for LASIK?

Young woman in hat curious about LASIK, Los Angeles

Although LASIK has helped millions of people reduce and even eliminate dependence on glasses, it is important not to assume that LASIK is the best option for you. The best way to determine if you are a good candidate is to be evaluated at the UCLA Laser Refractive Center for LASIK, Los Angeles.

What Makes Someone A Good LASIK Candidate?

Factors that determine a good candidate for surgery include prescription stability for your contacts and/or eyeglasses, age (you must be at least 18), and corneal thickness. Corneal thickness is one of the most important factors for LASIK surgery. Good surgical results depend on various factors, and you’ll have multiple tests performed during your preoperative examination, including corneal strength and thickness testing. But why does this matter?

In order for the LASIK laser to reshape the cornea to allow for clear vision free of glasses and contacts eye lenses, corneal tissue must be removed, referred to as ablation. The reshaping of the cornea is how the refractive error causing poor vision is corrected. The amount of corneal tissue that is removed from the stroma is called the ablation depth, and this depends on the degree of refractive error needed. In nearsightedness, (myopia) corneal tissue is removed from the center of your cornea to flatten the corneal surface. In farsightedness, (hyperopia) corneal tissue is removed from the periphery of your cornea to steepen the corneal surface. What’s left after the ablation is referred to as the “residual stroll bed”.

Why Does Corneal Thickness Matter?

Generally speaking, corneal thickness ranges from 500 to 600 micrometers. The FDA recommended that the residual stromal bed must be at least 250 micrometers thick for someone to be considered a good LASIK candidate. This 250-micrometer thickness of untouched corneal tissue, or residual stroll bed, is essential to reduce the risk of complications and preserve the integrity of the corneal tissue. Keep in mind, however, that many LASIK surgeons prefer to leave a greater margin of error for extra safety, usually leaving about 300 micrometers of residual stroll bed. This extra margin is not only safer but also allows for retreatments, also known as enhancements or refinements, if needed in the future.

The question then becomes how is corneal thickness measured. LASIK doctors use an ultrasound pachymeter. During testing, your eye will be numbed before the pachymeter probe will be placed in front of your eye, just touching the corneal surface. Measurements automatically taken by the probe will then be displayed on the monitor. Your doctor may instead decide to use an instrument that can measure corneal thickness without touching the eye, which includes the Orbscan, Pentacam, and anterior segment OCT. If your cornea is too thin, it may still be possible for you to undergo laser refractive surgery, so be sure to talk to your doctor about options available to you.

Candidacy for LASIK, Los Angeles

UCLA Laser Refractive Center has strict guidelines for determining LASIK candidacy. Not every person is a candidate for LASIK eye surgery. The refractive eye surgeons at UCLA are LASIK eye surgery specialists. Want more information about LASIK? Simply contact us at our Los Angeles LASIK office and speak with one of our patient counselors!

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