Don’t listen to what people say – listen to your doctor. FemtoLASIK or ReLEx® SMILE?

When you consider laser vision correction, you ask everyone around you for advice. Even knowing that the type of procedure will be decided by a specialist anyway, you seek out people who have had laser surgery and scour the Internet for information. There comes a point when you already feel like you could get a PhD in refractive surgery and its treatment methods, but you still don’t know which method would be best in your case.

Like many patients before you, you have the impression that the doctor will persuade you to use a particular method, because he just happens to specialize in it, and has a rather pale idea about others. Probably, you will think, it would be worthwhile to consult one more doctor, and one more, and… so on endlessly.

Friends who seemed credible and convincing to you at the beginning will suddenly start sounding suspicious… – maybe it just worked out in their case, because [insert list of factual arguments and conspiracy theories here], maybe they just got lucky.

Enough!

Reasoning this way, you will never decide to get laser vision correction. That you would reach even to the ends of the Internet, you still won’t get the knowledge – and especially the experience! – that your doctor has. So listen to your doctor: today he will explain to you how the FemtoLASIK method differs from the ReLEx® SMILE method?

Let’s start with the most basic information

Laser vision correction is a procedure performed on the cornea. It is one of the most amazing parts of the structure of our eye. We know that:

• The cornea of the human eye is responsible for 2/3 of its optical power
• The eye has a power close to 60 diopters, of which the cornea is about 42 diopters
• The cornea consists of 6 layers: epithelium, Bowman’s membrane, dermis, Duy layer, Descemet’s membrane and endothelium
• Corneal epithelium is the fastest regenerating tissue of the human body – complete replacement of epithelial cells occurs within 1 week

To get rid of the vision defect, it is enough to correct the power of the cornea – interfering with its thickness and curvature. The refractive surgeon has to reach the cornea’s dermis and make the correction.

Older methods of correction required the removal of the corneal epithelium (either mechanically or by laser), the more modern ones require only the creation of a corneal flap, and the most modern ones are already the so-called free methods.

FemtoLASIK(Femto- Laser-Assisted in situ Keratomileusis)

Method LASIK has a long tradition, and its uninterrupted development continues even in the present day. It was registered by the Food and Drug Administration(FDA) in 1999 as an effective surgical method for correcting vision defects.

In the method FemtoLASIK(Femto- Laser-Assisted in situ Keratomileusis) – which is the next step in the development of the modern LASIK method – thanks to a precise femtosecond laser, the surgeon makes a cut in the cornea, creating a thin flap 90 to 130 μm thick, known as a flap. The operation of the laser is computer-controlled, and the surgeon also has a microscope at his disposal, which guarantees maximum precision and selection of the diameter of the thickness of the separated corneal flap. It takes him only a few seconds to chip off this flake.

The femtosecond laser gives the refractive surgeon the ability to program custom flap shaping functions (flap size and shape, position adjustment, deviation size, and variable lateral incision angles).

Now the excimer laser enters the action, which ablates, that is, changes the shape of the cornea in its specific substance. The entire process proceeds according to pre-programmed parameters – different, maximally individualized for each patient.

Using such a dual-laser system, the doctor has an eye-tracker, or multidimensional eye movement sensor. So if one of your biggest fears was that during the procedure itself, the slightest movement of the eyeball could negate the success of the entire operation, now you’ve just lost that argument!

The high precision of the FemtoLASIK procedure means that people with large visual defects and thin corneas and a large pupil can also undergo it. It is assumed, FemtoLASIK correction is eligible:

• Myopia up to -10 diopters
• Farsightedness up to +4 diopters
• Astigmatism up to 6 diopters
• presbyopia – individual qualification
• higher order aberrations

The FemtoLASIK method is also used when a very small visual defect needs to be corrected, such as when work, hobbies or sports require falcon vision, it is possible to correct single diopters.

FemtoLASIK is one of the most precise and accurate technologies of laser vision correction. It also carries with it a very high possibility of individual approach to the patient – the latest generation lasers allow to adjust the shape and size of the corneal flap, as well as its position very individually. The same is true of the ablation profile. Thanks to this accuracy, it is possible to correct the most complicated and irregular astigmatism or various inhomogeneities on the corneal surface, all during the same vision correction procedure!

FemtoLASIK is a precise, extremely fast and painless method.Right after the operation, the patient may notice that he or she can see more clearly, but the eyes should remain protected for the rest of the day. After FemtoLASIK surgery, the patient may experience some discomfort from burning or stinging in the eye. Corneal regeneration should take 2 to 6 hours, so be patient at first.

ReLEx® SMILE (Small Incision Lenticule Extraction)

Method ReLEx® SMILE by Carl Zeiss is considered the next generation of laser vision correction. The ReLEx® SMILE procedure was first performed on the human eye in 2007 by Walter Sekundo using ZEISS’ VisuMax® femtosecond laser. And it became available in 2011 with the launch of ReLEx® SMILE (Carl Zeiss Meditec).

In this method – called the “keyhole” method – the corneal flap (flap) is not formed or cut. The procedure is performed through a small incision on the cornea, and is therefore minimally invasive. This means that there is also minimal interference with the cornea, so the healing process of the eye is very short. The procedure is performed with a VisuMax® femtosecond laser, delineating the tissue to be removed for better vision.

During the procedure, a so-called microlens (lenticule) is debulked in the corneal dermis, which is removed through a small incision. First, the VisuMax® femtosecond laser works deeper – the posterior refractive surface of the microlens is created, which is responsible for the main power change. Next, the anterior surface of the lenticule is prepared slightly higher. After incising the edges, the surgeon efficiently removes the microlens from the corneal parenchyma. The incision that breaches the corneal epithelium is much smaller than in methods that require debulking the flap.

The VisuMax® laser does not have an eye-tracking system to increase sensitivity to patient movement and track eye movements during the procedure. The ReLEx® SMILE method is single-stage, with the patient in one position throughout the procedure.

ReLex® SMILE is used only for patients with myopia from -0.5 to -10 diopters and astigmatism up to -5.0 diopters. After the procedure, you can perform all activities, rub your eyes, play sports, and there is no danger of corneal flap displacement.

Disadvantages of the ReLEx® SMILE method

• There is no possibility of additional treatment with the same method – there is no possibility of correcting the result of the operation by repeating the ReLex SMILE method. Correction is possible with LASEK/PRK, FemtoLASIK with thin corneal flap, CIRCLE methods….
• There is no possibility of using the so-called automatic static cyclorotation, important in the correction of astigmatism. However, many clinical studies have shown that the most accurate method for correcting astigmatism – in irregular astigmatism according to corneal topography – is the FemtoLASIK method.
• No correction of hyperopia.
• No correction of higher-order aberrations, e.g., coma, spherical aberrations or correction of aberrations based on corneal topography (topo-guided).

The lack of corneal flap in ReLEx® SMILE reduces the risk of corneal flap displacement that could occur after FemtoLASIK surgery in case of, for example, eye trauma, at the same time, unfortunately, it is the lack of flap that makes it impossible to perform vision re-correction (re-correction) with the same method. In the case of the FemtoLASIK method, the procedure can be repeated several times, as long as the corneal parameters and the general condition of the eye allow the patient to qualify for laser re-surgery.

Want to shine with knowledge even more?

Ahead of you is a handful of scientific data that can help you decide on laser vision correction.

If until now you were under the impression that you could get a PhD in refractive surgery and its surgical methods, now the habilitation is in front of you…;)

• Both refractive surgery methods described above involve interfering with the corneal tissue, which becomes slightly thinner. For this reason, each patient is examined to determine whether the thickness of the cornea in his case allows the procedure to be performed.
• In 2017, the FDA conducted a study that presented the post-operative results of FemtoLASIK (Contoura Topography guided LASIK (Alcon EX500)) and ReLEx® SMILE (Carl Zeiss) laser treatments. After 3 months, 93% of patients after FemtoLASIK are observed to have full visual acuity without correction (UDVA), while after ReLEx® SMILE this number is slightly less than 80%.
• The cornea heals faster after FemtoLASIK treatment.
• Three months after laser correction, you get equivalent levels of visual acuity with both FemtoLASIK and ReLEx® SMILE.
• It could be said that the only biomechanical advantage of ReLEx® SMILE over FemtoLASIK is that no corneal flap needs to be created. However, it has been proven that the cornea is equally weakened after the procedure in both methods.

A March 2017 study proves that both FemtoLASIK(Femto- Laser-Assisted in situ Keratomileusis) and ReLEx® SMILE(Small Incision Lenticule Extraction) procedures carry no risk of vision loss (as well as a significant risk to vision)