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What LASIK does
LASIK surgery uses a cool ultraviolet laser (called an excimer laser) to correct the shape of the cornea. This is the front surface of our eye, through which light rays pass on their way to the retina. They pass through the lens behind the cornea and form a tiny image on the retina, which is transmitted to the brain by the optic nerve.
Imperfect corneal shape
When the cornea is not perfectly shaped, the light rays bend at the wrong angle. Then they don’t focus on the retina but in front of it or behind it. This creates near- and far-sightedness respectively.
And when the cornea has little irregularities in its shape, the light rays come to the retina out of focus in certain areas, so that our vision has blurriness in different parts.
LASIK uses the excimer laser to vaporize tiny pieces of corneal tissue, so as to correct the corneal shape and surface. Then the light rays focus sharply on the retina and we see clearly.
Corneal flap
Before directing the laser beam on to the cornea to reshape it, Dr. Khanna cuts a tiny flap on the corneal surface and bends it back to expose underlying tissue. The laser works on that tissue and the flap is replaced, where it heals itself in a few days.
Not everyone is a good candidate for LASIK
If your corneas are too thin or too flat, LASIK is not a good answer.
Corneas too thin
In LASIK, the little flap is cut with a device called a microkeratome. If your corneas are too thin, Dr. Khanna may not be able to cut a good flap.
Corneas too flat
The purpose of LASIK surgery is to remove tiny pieces of corneal tissue to improve vision. But if the cornea is too flat, removing more tissue will make it even flatter, and this won’t improve vision. So people with extra flat corneas are not good candidates for LASIK surgery.
LASEK (E-LASIK)
LASEK (Laser Epithelial Keratomileusis) uses a different tool to create the tiny flap. It’s called a trephine and has an even finer blade.
The LASEK procedure is then like traditional LASIK, using the excimer laser to remodel corneal tissue, and the flap is carefully replaced.
The flap usually heals in a day or two, and you may feel some eye irritation during this time. Many patients wear a “bandage” contact lens that holds the flap in place while it heals but also allows oxygen to flow to the eye tissue. After a week or so you’ll have your new vision. This is a longer time than after LASIK, when the results are immediately noticeable.
Epi-LASIK
In Epi-LASIK, the small flap is cut and excimer laser used to vaporize excess corneal tissue, as in LASIK and LASEK. But in Epi-LASIK, a plastic, oscillating blade is used to create the flap, rather than the microkeratome or the finer-bladed trephine.
And instead of using an alcohol solution to loosen the flap’s edges before lifting it back, a very fine plastic blade is used, called an epithelial separator. Why?
Because in some cases, the alcohol solution can cause epithelial cells to die. An epithelium is a surface membrane, so in this context, it refers to the surface cells on the cornea. The eye must grow more epithelial cells around the flap’s edges to reintegrate it with the rest of the corneal surface.
Epi-LASIK results
As with LASEK, vision improvement occurs more slowly than it does after LASIK. For some, it’s evident after 3 or 4 days, and for others it may not be evident for 3 or 4 months.
But before Epi-LASIK, people with thin corneas were not able to have laser vision correction. Now they often can.
To learn more about LASIK and other vision correction procedures, please contact Dr. Khanna at the Khanna Institute of LASIK & Refractive surgery today.
Click here for 10 things you need to know about LASIK.
Click here for information on Allaying Fears about LASIK.
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| Los Angeles LASIK Surgery Disclaimer: Dr. Khanna serves eyecare patients in Los Angeles and surrounding areas. This site is for informational purposes only. It is not intended to be medical advice for those seeking laser vision correction, but to provide information about the Los Angeles, California LASIK Surgeon, Doctor Rajesh Khanna, M.D. Dr. Khanna proudly serves patients throughout Southern California and Orange County including Los Angeles, Bakersfield, Beverly Hills, Burbank, Camarillo, Malibu, Oxnard, Santa Barbara, Santa Monica, Thousand Oaks, Valencia, and Ventura. |
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