It is very difficult to find clear and uncluttered information about what is LASIK and how you find the surgeon of your choice. This page is written with you as the patient in mind. This page may be long and difficult to read but is a must read for anyone considering laser eye surgery. If there are still question, please feel free to contact us.
Surface (PRK) or Below Surface (LASIK)
Laser vision correction is done by either treating directly on the corneal surface OR lifting a thin layer of the cornea and placing the laser pulses below the thin layer and then replacing the thin layer in place.
If one treats directly on the surface, the surface cell layer (epithelium) is removed, pulses of laser are applied to the exposed cornea (Stroma). This is called Photo Refractive Keratectomy (PRK). The exact same concept with equal results are also referred to Advanced Surface Ablation, LASEK, and EpiLASIK. Advantages: No flap is created. This means there can be no complications with its creation. Disadvantages: Longer healing phase (weeks to months). Potential corneal scarring and haze formation. Greater risk of infection. Pain and discomfort although mild in most cases, can be harsh sometimes. Poor vision in the first week.
The most common laser vision correction procedure is LASIK which treats below surface. In order to treat below surface, a device is used to create a thin shaved layer off the surface. This layer is then folded back out of the way to exposed the inner portion of the cornea (stroma), the laser pulses are delivered, the thin layer is then replaced back in place. Advantages: Quick recovery of vision (hours to days). Minimal if any discomfort. Less risks of infection. Minimal to no risk of corneal scarring or haze. Disadvantages: Risks of complications in creation of the flap. Potentially greater relative weakening of cornea.
Custom, Optimized or Conventional
Both LASIK and PRK can be done either Custom, Optimized or Conventional!!!
The term conventional simply means doing it the same old way, it just sounds better. When you have your eyes tested, the lenses that are placed in front of your eyes and are asked "which is better, one or two?" is old style of measuring the prescription of your eyes. With this method only 85-90% of the total prescription of your eyes are measured. This same prescription is placed into the laser machine to create the correction. Advantages: Really, none in 99% of cases. Just simply cost. Disadvantages: Many of the "higher order aberrations" of the eyes are not treated. As a result the number of patients that experience glares and halos at nights are approximately 50% higher than custom (total about 15%), and the severity may also be greater. The accuracy is also less and the number of patients that end up having a second surgery to correct the prescription once again, an "enhancement," is about 10 to 20%, compared with custom retreatment rate of 2-5%. These factors play an enormous role in patient satisfaction from the procedure.
Wavefront Optimized treatment is a step slightly improved upon the conventional treatment. One of the main issues causing glares and halos after LASIK surgery with conventional treatment, was in increase in "higher order aberrations (HOA)." The most common type of HOA, causing the greatest fuzzy vision, is called "Spherical Aberration." In wavefront optimized treatments a standard correction factor for spherical aberration is added in for everyone, regardless of their pre-operative measurements. Advantages: Spherical aberration is treated such that many benefit. Also the cost for delivery of this treatment is much less expensive than Custom treatment. There is no personalization, so fewer exams and measurements, less personnel needed, and also, the royalty fees on the treatment are the same as the conventional treatments. Disadvantages: As there is no personalization to each eye, there are some eyes that could potentially have a greater spherical aberration after the treatment and therefore worse vision! Although wavefront optimized may be better that conventional treatment overall, it is still not as advanced as the Custom treatment.
Custom treatment requires the use of a second machine that measures the "wavefront" of the eye. The wavefront is basically a grid of lights (about 240 spots) that are shined in the eye and are recaptured once they exit the eye. These spots are then used to create a prescription map of the eye. With this method a greater percentage of the prescription of the eye is measured. Advantages: More accurate. Able to treat the "higher order aberrations" unique to the eye being treated which are not measurable in glasses. Less glare and halos at nights. Lower retreatment rate. Significantly higher patient satisfaction rate. Disadvantages: Cost. Rare few patients may not be candidates due to previous eye surgeries or very high prescription outside of the treatment range.
LASIK with Blade or Laser "Microkeratome"
The advantages of LASIK are gained by creating a thin layer from the surface of the cornea that is lifted and moved out of the way for the laser to reshape the cornea. This thin layer is created by a device called "microkeratome." The blade microkeratomes use a metal blade - just like a shaving blade - that oscillates about 10,000 times per second and moves forward on the cornea to shave that layer of the cornea. These devices are very accurate and do a great job for vast majority of the patients. Advantages: Cost. Rare patient with a corneal scar. Disadvantages: Severing of the nerves in the cornea and consequent dry eyes. Creation of the flap is where the vast majority of complications arise, including mechanical failures of the microkeratome, flap too thin, flap too thick, flap too big, flap too small, decentered flap, flap too short, flap cut off or a "free cap", flap amputation, flap slipping off, wrinkled flap, chatter of the flap bed, infection, and surely more that has been left off the list.
The laser microkeratomes is the new generation of devices that use laser rather than a blade to create a flap. The most commonly used and most popular laser microkeratomes in the United States is the IntraLase. The IntraLase is in its fifth generation and has been available since 2001. The laser device once placed on the eye, brings the image of the eye on the computer screen and allows the surgeon to customize the treatment for the patient. The surgeon can choose the size, the depth, the shape, and the flap edge angle as well as the centeration. Advantages: The capacity to customize for each patient. All the above list. elimination of all the complications of the blade microkeratome as listed above. Significantly less dry eyes. Better quality of vision. Disadvantages: Cost. Many surgeons due to the cost have chosen not to invest in this technology for their patients.