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Why is Corneal Thickness Important for LASIK?

Updated: Dec 1, 2023



If you are considering LASIK surgery, certain norms must be met to determine your suitability for the procedure. One crucial element that impacts the outcome of this procedure is Corneal thickness for LASIK. LASIK involves creating an incision in the outer Corneal layer and reshaping the underlying layers to improve vision. However, individuals with excessively thin Corneas may face a higher risk of complications following the procedure.

Laser-assisted in situ keratomileusis, or LASIK, is a common type of refractive surgery. It is a surgery that is approved by the FDA and is used to correct refractive errors that may include myopia (nearsightedness), hyperopia (farsightedness), and astigmatism.


Why is Corneal Thickness for LASIK Important?

The Cornea is like a clear window at the front of your eye. The shape of the Cornea can make your vision blurry, but it can be fixed by using a laser to change the Cornea's shape. This laser treatment involves removing some tissue from the Cornea to make your vision better.


The requirement for a specific Corneal thickness in LASIK is to ensure that an adequate amount of tissue remains in the Cornea after the removal process. Essentially, during laser eye surgery, the Corneal thickness is reduced, and it must initially be thick enough to withstand this reduction. The potential risks associated with LASIK in cases of thin Corneas make it an unwise choice.


Important Requirements for Corneal Thickness for LASIK

Corneal thickness is typically measured in micrometers or microns, with the average thickness being around 555 microns. During LASIK surgery, a flap is created. The thickness of the flap can vary between 90-160 microns, general average being 110 microns. which is approximately 110 microns thick. Following the creation and lifting of this flap, tissue is removed through laser ablation to correct refractive errors.


To ensure the safety of LASIK, it’s crucial to leave an adequate amount of tissue behind after the flap creation and tissue removal. This remaining tissue, known as the residual stromal bed, should measure a minimum of 250 microns. It plays a vital role in maintaining the Cornea’s stability. The amount of tissue removed depends on the severity of the refractive error. Therefore, individuals with a higher pre-treatment refractive error, such as -8.00, require a thicker Cornea compared to those with a refractive error of -3.00.


Before undergoing LASIK, a Corneal thickness test called pachymetry is conducted during your preoperative evaluation. This test assesses whether your Corneal thickness is above or below the average and determines if you meet the minimum Corneal thickness requirements for LASIK. The minimum required corneal thickness for Lasik surgery is generally considered to be 500 microns. In simple terms, LASIK is not recommended for individuals with thin Corneas.


Factors that Impact Corneal Thickness

Corneal thickness can be influenced by factors such as age, gender, ethnicity, and specific medical conditions. Let’s look at them individually:


Age: As we age, our Corneas tend to become somewhat thinner, making them less resistant to the pressure created during LASIK surgery. This might affect how well LASIK surgery works for older people. People with thicker Corneas usually have better results with LASIK.


But If your Cornea is too thin, you might consider other options like PRK or ICL, but you should talk to an eye doctor who knows about these procedures as certain criteria need to be fulfilled for these procedures as well.


Gender: Research indicates that calluses tend to be thicker in men compared to women. This difference may be attributed to variations in hormonal profiles between the two genders. Women who possess thicker Corneas may potentially make better candidates for LASIK surgery.


Ethnicity: Corneal thickness varies among individuals of different racial backgrounds. Research suggests that individuals of African descent tend to have thicker Corneas compared to those of European or Asian descent. These differences may be attributed to inheritable factors among various racial groups.


Certain medical conditions can also influence Corneal thickness. For instance, individuals with keratoconus, characterized by a thin, conical Cornea, may not be suitable candidates for LASIK surgery. Conditions like Corneal dystrophy, Corneal scarring, and prior eye surgeries can also impact Corneal thickness and may affect eligibility for LASIK surgery.


What if My Cornea is Too Thin for LASIK?

If your Cornea is too thin for LASIK, your doctor is most likely to recommend against proceeding with the surgery. While this might not be the news you were hoping for, your doctor’s guidance prioritizes your safety. LASIK poses significant risks for individuals with thin Corneas, and pursuing the procedure in such cases could result in deteriorating vision.


Alternatives to LASIK with Thin Cornea

If your Corneal thickness is not appropriate for LASIK eye surgery, there are alternative options available for you to consider.


Implantable Collamer Lens (ICL)

Instead of removing tissue from the Cornea, a biocompatible synthetic lens is inserted in the eye, positioning it between the iris (the colored part of the eye) and the crystalline lens. The calculations & the final power prescription for the ICL is determined in advance and tailored to meet the patient’s specific visual requirements.


Photorefractive Keratectomy (PRK)

This laser refractive surgery is quite the same as LASIK but doesn’t involve creating a flap. This approach conserves tissue, making it possible to perform PRK on thinner Corneas compared to LASIK. PRK requires a slightly longer healing period & may be associated with some pain in the first 2-3 days after the surgery.


Conclusion

Corneal thickness plays a crucial role in determining the eligibility for LASIK surgery. The required minimum corneal thickness for LASIK surgery is generally considered to be 500 microns, though many surgeons may go upto 490 microns depending on many other factors. It is also very important to assess the residual stromal bed thickness which should be a minimum of 250 microns. Factors such as gender, ethnicity, and age may impact the thickness of the Cornea. It is best to consult a doctor if you are contemplating going for a LASIK. It is essential to undergo a thorough examination so that you can be certain that your eye condition is suited for the surgery and ultimately have a great outcome.


 

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Medical Director & Senior Eye Surgeon

One of the best Cataract, Cornea and Lasik eye surgeons in Gurgaon.

Exp: 20 Yrs

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