How Does Corneal Thickness Affect LASIK Candidacy?
Millions of Americans suffer from refractive errors that result in impaired vision in the form of nearsightedness, farsightedness, or astigmatism. To correct these errors, patients often rely on prescription lenses, such as glasses or contact lenses. However, if a person’s vision prescription is stable and they are at least 18 years of age, there may be a better option. LASIK surgery reshapes the cornea to treat the most common types of refractive errors. This laser vision treatment improves a patient’s eyesight and reduces, or completely eliminates, their dependence on prescription lenses. While LASIK offers a number of benefits, it is not appropriate for all patients. Dr. Steven Chander examines the eyes to determine if LASIK can be safely and successfully performed. One key aspect that goes into determining candidacy for LASIK is corneal thickness. Our Chicago, IL patients can read on to learn more about the importance of corneal thickness when it comes to LASIK treatment.
The LASIK Procedure
For patients to understand why corneal thickness is an important aspect of determining LASIK candidacy, we must first explain the LASIK procedure. During LASIK surgery. Dr. Chander creates an incision on the surface of the eye. This incision creates a hinged flap that is lifted and folded back to grant access to the corneal tissues beneath. After making the necessary corrections to the underlying corneal tissues, the flap is put back in place so the tissues can heal. If there isn’t a sufficient bed of corneal tissues left after creating the LASIK flap and removing corneal tissues to correct refractive errors, then it will be more difficult for the eyes to heal. Insufficient corneal tissue has been linked to an increased risk of LASIK complications, which is why patients with thin corneas are not suitable LASIK candidates.
How Thick Do My Corneas Need to Be?
There are several factors that go in to determining if a patient’s corneas are thick enough for LASIK treatment. We must consider how thick the cornea is, how thick the corneal flap will be, and how much tissue will be removed during treatment.
The average corneal flap created during a LASIK procedure is 160 microns thick. Additional tissues will be removed during the LASIK procedure to address refractive errors. The amount of tissue that is removed will depend on how severe a patient’s prescription is. On average, we remove 12 to 14 microns of tissue for each diopter of prescription power. After this corneal tissue is removed, patients should have at least 250 microns of corneal tissue remaining. Any less than this would lead to an increased risk of surgical complications.
On average, a person’s cornea is about 540 to 550 microns thick. Assuming a patient’s cornea is of average thickness (550 microns), they can lose 160 microns of tissue for the corneal flap and another 112 microns of tissue for the prescription treatment (this would be 8 diopters of prescription power) and still have 278 microns of corneal tissue remaining. However, if a patient’s corneas are less than average, they may not have the 250 microns of tissue remaining that is necessary to promote healthy healing. The only way to know for sure if the corneas are thick enough for LASIK treatment is to schedule a personalized consultation and eye exam with an experienced LASIK surgeon such as Dr. Chander.
If a patient’s corneas are deemed too thin for LASIK treatment, there are alternatives. In addition to prescription lenses, Dr. Chander offers PRK, or photorefractive keratectomy. PRK reshapes the corneal tissues to improve vision, but it does so without creating a corneal flap. While PRK recovery is slightly longer than LASIK recovery, this is an excellent option for patients who are not LASIK candidates.
Laser vision correction can improve your vision and provide you freedom from prescription lenses. To learn more about our laser vision correction procedures, including LASIK, IntraLase® LASIK, and PRK, contact us at your earliest convenience.