My LASIK research for hyperopia and astigmatism

How important is the equipment that your doctor uses for LASIK?

We have established that the way LASIK can be executed could be bladeless (using another laser to make the cut and create the corneal flap) or have a doctor use a manual blade called a microkeratome.

Another important advance in laser eye surgery over the past couple of years has been topography guided “custom lasik” scientifically called Topography-guided ablation.

So what is Topography-guided ablation (“custom lasik”)? It is a unique treatment where prior to your surgery the doctor will take corneal scans, basically measuring the reflection of light on your eye to create a custom process to give you better results. Remember, not two eyes are the same.

Topography-guided ablation can be used to address corneal issues using a custom map telling the laser where to make corrections that are unique to your eye. It uses different ablation strategies than wavefront guided LASIK.

An excellent article on Pros and Cons of Topography-guided Ablation (Review of Ophthalmology, July 2012).

Another article praising Topography-guided procedure raising the bar in laser vision correction outcomes (Ophthalmology Times, February 2016).

Now that you know that custom lasik exists in addition to the regular lasik, let’s talk about the most important part of this surgical procedure, the laser itself.

Not all laser machines are the same. This is trivial to understand and it does make a difference in the overall surgery and possible outcomes.

Let’s talk about how a laser is effective.

A laser machine is creating custom corrections in your cornea to restore your vision, it is using an algorithm set by the manufacturer of the laser machine. There are several companies (Schwind, Nidek, Wavelight, etc) with different algorithms and different intensities (Hz) of laser.

After the corneal flap is created, the doctor will place a couple of drops in your eye before starting the laser. The effectiveness of the laser depends on the surface of your cornea staying hydrated while the laser is making its corrections. It is normal for the cornea to start drying up after the corneal flap is created.

An excimer laser operates at a set “speed” measured in hertz (Hz) depending on the machine your doctor uses you may get a machine that shapes your cornea using a laser pulse of either 250Hz, 500 Hz, 750Hz or 1050Hz.

Faster is better for the overall success and correction of your eyes. As I explained during the surgery the cornea is revealed and it begins to dry up. For example if your doctor uses a 500Hz excimer laser to correct 4.0D of myopia, the WaveLight® EX500 Excimer would take 5.6 seconds to make this correction (1.4 second per dioper of correction * 4.0 diopers to correct)

Now let’s do the same surgery using older laser technology for the same eye, assuming the doctor uses a MEDITEC MEL 80 Excimer Laser System (made by Zeiss) which operates at a speed of 250Hz (3.0 second per dioper of correction * 4.0 diopers to correct) it would take twice as long (12 seconds) for the same surgery on the older laser.

It is also important to highlight that newer lasers remove less corneal skin than older lasers or procedures. Removing the least amount of cornea during your surgery is important so that you are able to get another surgery later on in life when other vision problems like presbyopia appear. (article from the American Optometric Association on adult vision after 40 years old)

Richard A. Levinson, MD (Colorado Eye Surgeon) on his comparison of two different laser systems has stated “…Basically, in my experience, both Laser Systems are excellent but the advantage of the 8 times faster treatment with the WaveLight is more clinically important than the theoretically more precise mathematical modelling and astigmatism mapping (see below) of the VISX Star S4.” (source)

Finally, here is a comparison of the 6th generation Excimer Lasers (Biomed Central, March 2015) . Unfortunately this does not include the fastest and newest Excimer laser in the world, the AMARIS 1050RS (1050 Hz laser pulse)

On the next page I share where to find doctors using the latest and fastest excimer laser in the world.