LASIK Technologies ExplainedIncluding EagleVision Lasik

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Last updated 10/8/2019
LASIK eye surgery technologies, Assil Eye Institute

Is there more than one kind of LASIK?

Absolutely! There’s a whole spectrum of LASIK technology being marketed today, ranging from what many consider obsolete technology to leading edge state-of the art laser vision correction. And everything in between.

 

We’ll review some of the distinctions to help you decide which LASIK surgery may be best for you.

 

Before discussing what is unique about each of the five generations of LASIK technology, we should first review how LASIK surgery corrects your vision.

How does LASIK work?

 

Your vision prescription is essentially determined by two main factors:

 

  1. The length of your eyeball from front to back.
  2. The shape of your cornea (the transparent surface or “windshield” through which light is filtered and focused onto your retina which, in turn, processes images).

 

Because two thirds of your eye’s ability to focus light resides in the cornea, vision correction research has centered on ways to improve the cornea’s ability to refract (focus) light.

 

Your vision prescription is known as your refractive error – in other words, the amount by which your cornea’s focusing ability deviates from normal 20/20 vision. 

 

LASIK was developed to correct refractive error by using laser energy to reshape the cornea so that it can focus light accurately onto the retina. 

What do all LASIK surgeries have in common?

The following steps are common to all LASIK procedures:

  1. The surgeon makes a very thin incision in the outermost layer of the cornea. This incision can be done manually, using a blade called a microkeratome, or with a bladeless technique using a Femtosecond laser. At AEI, we always perform this step with a laser. 

    The laser provides dramatically better precision in determining the incision depth and shape than is achievable manually using a blade, which is quickly becoming obsolete. 
  2. In all of the laser surgeries below except one, this incision creates a corneal flap, which is then flipped open like the cover of a book. 

  3. Next, another laser (the Excimer laser) uses gentle UV light to sculpt the newly exposed corneal tissue according to a treatment plan designed to improve the cornea’s light refracting ability.
  4. After the vision correction is done, the flap is flipped back into place, like closing the cover of a book. No stitches are needed because the cornea heals naturally and quickly on its own.

 

Now that we’ve explained the LASIK fundamentals, let’s look at the five generations of LASIK technologies available today

1st Generation (1G) LASIK:

Basic LASIK with Keratome Blade

Technique: Manually cut flap plus unguided excimer laser corneal sculpting.

 

In “old fashioned” LASIK, the surgeon uses an instrument known as a microkeratome to manually cut a thin, hinged flap from the cornea (the transparent outer surface of the eye). The flap is folded open like a book cover and then laser energy is applied to reshape the cornea’s exposed layer for vision correction. 

 

Pros of Basic LASIK

    • None, other than possibly price, as the only high-tech device needed is a single (Excimer) laser.

 

Cons of Basic LASIK

    • There are many downsides to this technique, all of them involving an inferior end result. 
    • We have not performed this surgery at AEI in over 15 years and it is not recommended today under any conditions. It is usually only found at “bargain LASIK eye centers.

2nd Generation (2G) LASIK:

Standard Bladeless LASIK 

Technique: Femtosecond Laser made flap plus unguided excimer laser corneal sculpting

 

Introduced in 1999, this bladeless LASIK approach is similar to traditional LASIK, but instead of cutting a flap by hand using a microkeratome, the surgeon cuts the flap using a special infrared laser called a femtosecond laser that’s capable of making exquisitely refined microscopic incisions.

 

The cornea is then sculpted with an excimer laser using gentle UV light for vision correction.

 

Pros of Standard Bladeless LASIK:

    • Cost Savings is the only real upside of this type of LASIK. Because only two laser technologies are used, this forces the patient into a “one size fits most” methodology.

 

 Cons of Standard Bladeless LASIK:

    •  There is little in the way of surgical planning that is customized for the individual patient. 
    • This is another very basic LASIK procedure usually only found at “bargain” LASIK eye centers.

 

Lebron James, Assil Eye Institute LASIK patient

 

3rd Generation (3G) LASIK:

ContouraVision

Technique: Femtosecond laser made flap and Topography guided Wavelight Excimer laser corneal reshaping

 

Contoura Vision is a more advanced LASIK technique that was designed to provide surgeons the ability to perform personalized vision correction for patients with nearsightedness, farsightedness and/or astigmatism.

 

Contoura builds on the bladeless LASIK approach by using the Wavelight Topolyzer VARIO device. This device was the first to create a custom laser surgery plan for each eye based on its measurements of not only the vision power (called refractive error), but also of the cornea’s unique topography (surface elevations and dips). 

 

By uploading this additional data into the sculpting (Excimer) laser, Contoura technology offered a big step forward in vision correction. FDA clinical trials showed that 92.6% of Contoura patients had 20/20 vision or better and more than 30% of patients achieved better visual vision than they had previously enjoyed with glasses.

Contoura out-performed Standard Bladeless LASIK because it decreased post-op complaints of light sensitivity, night driving problems, reading difficulty, glare, halos and starbursts.

 

Pros of ContouraVision topography guided LASIK

    • The process is better than conventional bladeless LASIK, especially for patients with a highly abnormal corneal shape.

 

Cons of ContouraVision topography guided LASIK

      • The technology used by Contoura for measuring corneal topography (developed 35 years ago) only measures one of several factors responsible for your eye’s focusing power, so it offers a limited solution to your vision problem by focusing solely on the cornea’s contribution to your focusing ability. 
      • A key factor known as the Wavefront also has great bearing on your eye’s focusing ability and is not taken into consideration by Contoura. A Wavefront is basically the way that light travels through the entire eye, not just the corneal surface. 
      • Everyone’s Wavefront is highly unique, like a visual “fingerprint”. ContouraVisionTM assumes that the same Wavefront exists for all patients (one size fits all) so, while it customizes your surgical plan for your eye glass prescription and corneal topography, it does not take into account your unique Wavefront.

 

SMILE LASIK

SMILE Technique: Flapless approach: A Femtosecond laser cuts a very small incision at the side of the cornea in order to carve out and remove a small disc of tissue from the middle corneal layer.

 

SMILE LASIK, which stand for "Small Incision Lenticule Extraction) LASIK" is a nearsighted only laser vision correction procedure with a different surgical approach than any other LASIK procedure.

 

SMILE technology was developed in 2011 to make nearsighted LASIK correction to more people by bringing down the cost by using a one laser process that only works for only for nearsighted correction.

 

It gained traction overseas in India, Korea and China back in 2011 while awaiting United States FDA approval. Unfortunately, SMILE comes at the expense of accuracy because it is a one laser process. Thus it doesn’t involve the refined optics measurement and surgical planning that takes place with today's more advanced LASIK protocols (such as iDesign).

 

With SMILE, a Femtosecond laser carves a small disc of tissue just below the cornea’s surface and this small disc (called a lenticule) is removed through a tiny curved incision at the side of the cornea and discarded. With the lenticule removed, the shape of the cornea is modified, and the patient’s nearsightedness (and only nearsightedness) is corrected.

 

Pros of SMILE LASIK


      • Similar to Basic LASIK (which uses an Excimer Laser + metal blade Keratome) SMILE only uses a single laser (the Femtosecond) and a simple surgical plan for vision correction and so the treatment is much more economical.

 

Cons of SMILE LASIK

Although SMILE surgery is advertised as an advanced vision correction technique, it has only gained popularity in places like China (where modern LASIK is not readily available), it has some significant limitations. These includde:

 

      • Because a single laser (Femtosecond) is attempting to perform both the corneal incisions and the corneal sculpting, the reshaping is somewhat crude as compared to the Excimer laser’s sculpting, which takes place at the molecular level.
      • SMILE is limited to correcting simpler forms of nearsightedness. It cannot readily correct farsightedness, significant astigmatism, or high nearsightedness. It also, cannot correct any Higher Order Aberrations (that can only be corrected with 4G and above LASIK technology).
      • In clinical trials, a lower percentage of patients achieved 20/20 vision following SMILE surgery than those who chose the most advanced modern LASIK vision correction available at the time. Whereas 93% of modern LASIK patients reported even better or the same vision as they had with glasses or contacts, only 70% of SMILE patients met this threshold.
      • Although SMILE originally claimed to have fewer post-op dry eye symptoms than LASIK, this has not been borne out over time and current studies do not show there to be any real difference.
      • SMILE patients take slightly longer than LASIK patients to achieve crisp vision following surgery: most LASIK patients achieve 20/20 or better within 24 hours of surgery whereas SMILE patients might take several days or not at all.
      • If, following a SMILE procedure, further subtle vision corrections are necessary (called enhancements), a second SMILE procedure cannot be performed because this technology isn’t capable of this level of fine-tuning. Therefore, you will need to undergo one of the other LASIK or PRK surgeries to gain any further vision enhancement.
      • Since SMILE is less likely than other forms of LASIK to achieve 20/20 vision, the need for post-op enhancement surgery using these alternative technologies is increased.

 

Schedule your LASIK  consultation now

 

4th Generation (4G) LASIK:

iDesign™ LASIK

Technique: Femtosecond laser made flap plus Corneal Topography combined with Wavefront guided excimer laser corneal sculpting

 

iDesign takes LASIK technology one step beyond Contoura by more precisely measuring not only the corneal surface topography (namely the minuscule elevations and dips in the cornea’s surface), but also by measuring the exact optics of each eye (prescription measurements even more detailed than you get when the optometrist measures you for contacts or glasses). 

 

This level of precision creates a significantly better laser surgical plan than what is achievable by first, second or third generation LASIK.

 

iDesign™ captures your personal optics using Wavefront technology which creates a completely personalized 3-D map of your exact visual pathway (the path that a light ray travels from the front of the eye, through the cornea and all the way to the back of the retina). It does this by dividing the visual surface area of your eye into over 1,200 adjacent zones and measuring each zone’s prescription individually. 

 

This data is then used to program the sculpting laser to treat each zone individually (as opposed to other laser systems which correct the entire visual surface for just one prescription measurement). iDesign is the only FDA approved system with Wavefront technology.

 

By combining Wavefront data and topography data, iDesign is able to create a personalized program that guides the laser during surgery to correct each eye’s unique refractive error.

 

Pros of iDesign Wavefront and Topography guided LASIK

      • Wavefront technology is able to measure and treat eyesight deviations beyond simple nearsightedness, farsightedness and astigmatism.
      • These other deviations from normal vision are called lower-order aberrations (or LOA) and are exactly what is being measured when the eye doctor examines your eyes using a machine called a phoropter to fit you for eyeglasses or contact lenses.
      • Wavefront goes one step further by also measuring complex optical imperfections called higher order aberrations (HOA) that cannot be corrected with regular eyeglasses.


HOAs are responsible for symptoms like glare, halos, starbursts and contrast sensitivity. The refinement that’s achievable using Wavefront data to guide the laser are like an artist using a paint brush, versus an airbrush.

      • In large studies using iDesign, patients’ average post LASIK vision correction exceeded their best pre-Lasik vision correction wearing glasses or contacts.
      • iDesign was found to out-perform Contoura™ with regard to post-op visual acuity and contrast sensitivity1
      • iDesign also has a lower risk of developing post-op night glare as compared to Standard LASIK.

 

Cons of iDesign Wavefront and Topography guided LASIK

      • Technically, there are no downsides to this technology. The only downside is cost: this approach is more expensive because it requires the integration of three sophisticated technologies (Excimer Laser, Femtosecond laser and iDesign) to create a customized treatment plan.

 

5th Generation (5G) LASIK:

EagleVision

EagleVision Technique: Femtosecond laser made flap + customized flap re-design + iDesign topography with Wavefront-guided Excimer laser corneal reshaping + customization of iDesign treatment algorithm.

 

The very latest LASIK protocol is known as EagleVlsion, which stands for Elliptical-flap Aberrometry Guided Laser Enhanced Vision.

 

Developed by renown LASIK expert Dr. Kerry Assil, EAGLE combines the best surgical techniques and technology currently available.

 

How EagleVlsion™ works:

 

The EagleVIsion Protocol begins with careful measurements:

      • Like iDesign LASIK, the EagleVision approach uses Wavefront technology that sub-divides the eye's ¨seeing¨ surface area into 1240 adjacent zones and measures each one's focusing capacity (known as refractive power). Other optical imperfections that can’t be corrected with glasses are also measured. 
      • Next, the cornea's surface is scanned to precisely measure the elevations and dips of each of these 1240 unique zones in order to create a detailed 3-D map of your eye's surface.

 

EagleVlsion LASIK then takes LASIK to the next level by customizing two key components of LASIK surgery:

Treatment plan customization

The EagleVIsion protocol uses custom algorithms developed by Dr. Assil to further refine the laser’s surgical treatment program to account for patient age, lifestyle and eye shape. This allows us to give every eye the most personalized treatment program available anywhere.

 

Corneal flap customization

The EagleVIsion corneal flap has been totally redesigned to be more ergonomic. It has been our experience that this not only provides safe access to a larger corneal treatment area, but also minimizes the risk of flap complications and post LASIK dry eye symptoms.

 

Pros of EagleVIsion LASIK

      • Ergonomic flap design offers a larger treatment area, added protection against eye injury and quicker healing
      • EagleVlsion™ achieves sharper post-op visual acuity than other LASIK technologies
      • EagleVlison™ has a lower incidence of post-op Dry Eye findings.
      • EagleVlsion™ achieves greater flap stability versus other LASIK surgeries

 

Cons of EagleVIsion LASIK

      • Just like iDesign LASIK the only con of EagleVIsion is that this technology is more expensive.
      • EagleVIsion requires the integration of three different refined technologies: Excimer Laser, Femtosecond laser and the iDesign as well as the accompanying treatment planning using an algorithm that is personalized for each patient. This level of customization comes with an increased cost.
      • This approach also requires a very experienced surgeon and surgical team due to the extremely high level of customization and technology employed. The surgeons at Assil Eye Institute have been personally trained by Dr. Assil and have the degree of skill and experience to deliver the very best outcomes available today.

 

Schedule your LASIK consultation now.

 

 Refrences:

 

  1.  J Refract Surg. 2015 Jun;31(6):398-405. doi: 10.3928/1081597X-20150521-06
  2. Assil, K. K., & McCall, T. (2005). Temporal hinge laser in situ keratomileusis: maximizing treatable stromal bed area. Journal of cataract and refractive surgery, 31(6):1139-1144.

 

  • Dr. Kerry Assil, Beverly Hills LASIK and Cataract Surgeon

    Kerry K. Assil, MD, is regarded as one of the world’s foremost experts in refractive surgery, having made significant advances in the field with his numerous inventions. Additionally he has the unique distinction of having trained thousands of eye surgeons in the latest refractive surgical techniques.

     

    Dr. Assil has authored more than one hundred textbooks, textbook chapters and articles on refractive surgery and has appeared regularly on major television network news programs as a pioneer in refractive surgery. He also leads educational forums for other eye care professionals, which have included featured lectureships at Harvard University, Johns Hopkins University and Tokyo University.

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