If You Have a Thin Cornea, Can You Get LASIK?

People with thin corneas often wonder why LASIK will not correct their vision problem. After all, it is used to help people see better who have been diagnosed with glaucoma, cataracts, or refractive errors. But if your corneas are too thin, you are not a candidate for LASIK.

Why Those With Thin Corneas Cannot Get LASIK

LASIK requires that you have sufficient corneal tissue, so it can be reshaped. If your cornea is too thin, you may end up with worsening vision problems if you attempt to remove tissue from it.

The use of a femtosecond laser to make a flap allows for high levels of accuracy, but you still have to make sure you don’t remove too much of the corneal layer.

Performing LASIK on thin corneas can lead to a greater risk of developing post keratorefractive ectasia. This unfortunate complication biomechanically weakens the cornea. Researchers have found that a preoperative corneal thickness of < 500 μm is the most common risk factor in the development of ectasia.

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Symptoms of Ectasia

Symptoms of corneal ectasia include blurriness, an increase in the symptoms connected to myopia (nearsightedness), and dry eye. 

Keratoconus is a progressive form of ectasia, which can lead to the development of a cone-shaped cornea.

Treating Corneal Ectasia

While eyeglasses are used to treat corneal ectasia, the newest procedure is known as CXL. This is a treatment option that improves the structure of the cornea by creating cross-links between collagen lamellae (each tissue layer). 

The doctor stops the progression of ectasia with the use of ultraviolet-A and a surface photosensitizer (riboflavin). This process may be considered when the condition is not advanced. 

Traditionally, penetrating keratoplasty was used to treat ectasia. However, the trend is shifting to a more targeted approach, such as deep anterior lamellar keratoplasty, also referred to as DALK. 

During the procedure, the surgeon removes the cornea’s stroma (deep connective tissue), while leaving the Descemet’s membrane and the outer covering of the cornea or the endothelium.

A Thin Cornea Diagnosis

Ultrasound pachymetry is the top method used for measuring the thickness of a cornea. This test can be administered in less than a minute for both eyes.

Clinicians may also use non-contact methods. For example, Orbscan II features topographic details of the cornea, including a corneal pachymetry map through the use of a slit scanning technology.

Alternatives to LASIK for People With Thin Corneas

If your cornea is too thin for LASIK surgery, there are alternatives available to correct your vision. Surgical procedures designed to help people with a thin or flat cornea include LASEK, phakic IOLs, Epi-LASIK, or a refractive lens exchange.

LASEK

One of the best modern alternatives for LASIK is LASEK. Instead of using a blade or laser light, the surgeon administers an alcohol-based liquid to soften the outer portion of the cornea. This enables the doctor to follow up and use the laser with ease. 

This less invasive approach is desired by some, as it has a low infection rate. While the recovery rate is not as short as LASIK, the operation is viewed as safe and successful.

Phakic Intraocular Lens Implant

For patients who have natural lenses that need replacement, phakic intraocular lens implants offer people with thin corneas a viable solution. The process does not involve cutting or peeling back any corneal layer. Instead, small parts of the cornea stay intact and an artificial lens, made of silicone or plastic, is inserted.

This lens is placed between the cornea and iris, so the patient can focus and see better. While the lens is intended as a permanent solution, it can also be removed if needed. 

Recovery may vary depending on the type of IOL used. However, most patients report vision improvement within 24 hours after the surgery.

Epi-LASIK

Epi-LASIK is another option for those with thin corneas. This procedure is sometimes viewed as less invasive than LASIK. The surgeon uses a plastic blade to lift the epithelium, so they can separate it from the inner part of the cornea. 

They then use a laser to reshape the corneal inner tissue. After this step, the surgeon inserts a contact lens to aid in recovery. If you have a thin cornea and wish to recover quickly, you might opt for this treatment plan.

Refractive Lens Exchange Procedure

The refractive lens exchange procedure is recommended for anyone who is not eligible to undergo traditional corrective surgery. The surgeon uses a laser to remove the crystalline lens of the eye, so they can replace it with an intraocular lens (IOL). 

This surgery helps the patient focus better and may be used to correct nearsightedness (myopia), farsightedness (hyperopia), or astigmatism with excellent results. 

The results of the surgery generally last a long time. That’s because the aging process does not affect the IOL. Patients who undergo this procedure do not develop cataracts.

You Have Options

You can  improve your vision even if your cornea is thin. Visit an eye doctor and assess the alternatives available to you. They can guide you on the best choice for you considering your corneal thickness.

References

1. Technology Helps to Diagnose Corneal Ectasia. (April 2018). Optometry Times.

2. Ectasia After Keratorefractive Surgery: Analysis of Risk Factors and Treatment Outcomes in the Indian Population. (June 2020). Indian Journal of Ophthalmology.

3. CXL for Corneal Ectasia: Reshaping the Future of Treatment. (April 2014). American Academy of Ophthalmology.

4. DALK. (September 2022). American Academy of Ophthalmology.

5. Corneal Stroma. (2021). Anatomy of the Eye and Orbit.

6. Descemet’s Membrane Development, Structure, Function and Regeneration. (August 2020). Experimental Eye Research.

7. The Importance of Corneal Thickness. (2022). Glaucoma Research Foundation.

8. Measurement of Central Corneal Thickness Using Ultrasound Pachymetry and Orbscan II in Normal Eyes. (January–March 2015). Journal of Ophthalmic Vision & Research.

9. LASEK. (November 2022). EyeWiki, American Academy of Ophthalmology.

10. What Are Phakic Lenses? (January 2018). U.S. Food & Drug Administration.

11. A Closer Look at the Epi-LASIK Procedure. (August 2004). Review of Optometry.

12. A Review of Refractive Lens Exchange. (November 2022). Review of Optometry.