What is laser vision correction – LASIK,Epi-LASIK, PRK, Intralase?

By November 4, 2009 Uncategorized No Comments

Laser vision correction refers to any surgical procedure that uses an excimer laser to reshape the cornea. The cornea is the clear surface on the front of the eye through which you can see the iris (colored part of the eye) and the pupil. The laser is used to vaporize the tissue in a precise pattern which reshapes the corneal surface such that dependence on glasses or contact lenses is reduced or eliminated. This process of vaporizing corneal tissue by the excimer laser is called ablation. In Calgary there are several surgeons who offer a variety of laser vision correction options. The main four treatments are no-flap treatments which include Epi-LASIK and PRK, and flap treatments which are LASIK and Intra-LASIK.

The surgeon who performs the procedure is an ophthalmologist who is a medical doctor (MD) with a specialty in the diagnosis of eye disease, treatment of eye disease, and eye surgery. The surgeon should be board certified. A surgeon who is board certified in the United States is designated as a Diplomate American Board of Ophthalmology (Dipl. ABO) and in Canada as a Fellow of the Royal College of Surgeons of Canada (FRCSC). There are often optometrists who work in association with an ophthalmologist who may do the initial assessment at some centers. Other staff such as technicians will also participate in your care.

The types of staff involved in your care may include:

Ophthalmologist (MD): medical doctor specialized in eye care and eye surgery
Optometrist (OD): doctor of optometry trained in medical eye care
Certified Ophthalmic Medical Technician (COMT): the highest technician
designation that assistants in eye care can achieve through the Joint
Commission on Allied Health Personnel in Ophthalmology (JCAHPO)
Certified Ophthalmic Technician (COT): second highest level of JCAHPO
certification held by assisting staff
Certified Ophthalmic Assistant (COA): first level of certification available to
eye care assistants through JCAHPO
Counselors: staff specializing in giving detailed information to patients.
Receptionist: staff who will be involved in scheduling appointments.

Pay attention to the quality of the front office staff including reception and secretaries. A well run center should have prompt and courteous care starting from your initial telephone inquiry and throughout your visits. If you choose to undergo surgery you will be spending time with a variety of staff members during your testing, counseling, surgery, and post-operative care.

Laser vision correction is also called refractive surgery or laser eye surgery. The procedures can be divided into two groups: those with flaps and those without flaps.

The most commonly available specific types of surgeries are:

Photorefractive keratectomy (PRK): the original no-flap surgery introduced in
in the US in1988 by Margueritte MacDonald.
Epi-LASIK: the latest no-flap procedure in which an epikeratome is used to
remove the outer epithelial layer to prepare for laser application.
Laser in situ Keratomeleusis (LASIK): the first flap procedure introduced in the
1990s in which uses a mechanical microkeratome to create a flap.
Intra-LASIK: a newer flap procedure which uses a femtosecond laser to create a
flap.

For PRK and Epi-LASIK the surface corneal epithelial cells are removed and the laser is applied directly to the corneal surface. For PRK the surface cells can be removed using dilute alcohol or with a brush. For Epi-LASIK an automated device called an epikeratome is used to remove the surface cells to prepare the corneal surface for the laser reshaping.

PRK has been around for over two decades and has an excellent long term safety record. Epi-LASIK is a newer technique that creates a precise epithelial removal that will help speed recovery. Because there is no flap to protect the surface while healing, PRK and Epi-LASIK result in more discomfort for the first few days after surgery and take four to ten days before the vision is recovered enough to resume driving and/or work. Medicated drops may be recommended a few times per day for a number of weeks or months after surgery. The long term vision results are excellent. The simplicity of the surgical technique means there is a lower chance of complications during surgery and no flap that could become damaged or dislodged due to injury in the future. Recently many surgeons have returned to PRK and Epi-LASIK as their recommended vision correction surgery due to the low rate of complications.

With LASIK and Intra-LASIK a corneal flap is created and the laser treatment is applied to the bed of tissue under the flap. LASIK was developed in the 1990s. LASIK is a combination of an older technique called lamellar keratoplasty in which a corneal flap was created and PRK. It has been called “flap and zap” in the past. For LASIK a mechanical device called a microkeratome is used to create a corneal flap. Flaps can range in thickness from 90 microns to 180 microns depending on the device used. For Intra-LASIK an ultrafast femtosecond laser is used to create the flaps.

Vision recovery following a flap procedure is quicker than with a surface treatment. In an uncomplicated case the patient may expect some discomfort and blurred vision for the first twenty-four hours. By the following day in most cases patients will be legal to drive, although there is long term healing that will be occurring so some patients may find the vision continues to sharpen for a number of days to weeks. There is a higher risk with flap procedures due to the complexity of creating the flap and the possibility that the flap could become damaged or shifted if a future eye injury occurs. In rare cases flaps may be shifted even months or years later. In most cases common sense eye safety should protect you from this type of injury. However, if you are in a high risk occupation or have high risk hobbies PRK or Epi-LASIK may be a better choice. Although higher risk, some consumers will opt for LASIK or Intra-LASIK due to the shorter recovery.
There may be reasons why a specific type of vision correction surgery may be recommended as safest for your individual case. Alternatively you may be given a choice of procedures, in which case you will need to weigh the risks and benefits of each procedure to make the choice that is right for you.

Regardless of the type of treatment you choose – flap or no-flap – the laser reshaping will be the same. Each center will have a different laser which is capable of different laser patterns. Some systems such as the Visx S4 IR can do a true wavefront treatment which can treat both the prescription as well as the higher order aberrations. The difference between a wavefront laser pattern and a non-wavefront pattern is like the difference between a tailored suit and an off the rack suit. Some systems will do a treatment with a specialized blend zone called an aspheric treatment. Aspheric treatments are not true wavefront treatments.

Your choices for laser vision correction include:
1. Flap or no-flap.
2. For flap treatments the choice is LASIK or Epi-LASIK.
3. For no-flap treatments the choice is Epi-LASIK or PRK.
4. Choice of surgeon & surgical center.
5. Choice of wavefront treatment (if available) or non-wavefront treatment.

If you have the time to undergo an assessment at more then one center you will be able to learn more about the options available at each center. For more information or to book an assessment, contact us at 403-547-9775 or http://www.westernlasereye.com/.

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