CXL and laser vision correction

There are several ways to improve your eyesight after cross-linking, and these include: special contact lenses, intrastromal rings and wavefront-guided PRK.

Importantly, none of these approaches slow or stop the progression of keratoconus – only cross-slinking can achieve this. Contact lenses, intrastromal rings and the excimer laser are more a means of improving visual quality.

The Goal of Laser Surgery

The goal of keratoconus laser surgery is to achieve better vision and visual acuity – in combination with lenses. “Vision” and “Visual acuity” do not mean the same thing. Visual acuity is purely a description of how small a letter patients can see on a vision test chart (it doesn’t matter if the letter is blurred or the patient sees three of them, the smallest sized letter the patient can read defines their score. “Visual acuity” says nothing about the quality of their vision, and the laser surgery is intended to reduce the irregularities in the cornea that cause these visual disturbances and make special contact lenses fit and work better.

Improvement of picture quality

There are two images below: the image on the left gives an example of good picture quality, and the arrow points to the 80% visual acuity line. The image on the right gives an example of poor visual quality, and again, the arrow points to the 80% visual acuity line. You can probably read both lines now, and the patient’s visual acuity would be 80% in both cases. However, you can see for yourself that the picture quality is completely different.

And this is the typical case of keratoconus: even if a certain visual acuity can be achieved, the quality can still be extremely poor. This is where the laser can help.

Same visual acuity, different image quality.

What can I expect?

In most cases, there is an improvement in visual acuity and image quality. Predicting outcomes in individual cases can be difficult – this type of laser is not a “simple” laser for treating regular refractive errors or astigmatism, but is instead a complex restorative procedure. Complications are very rare, but can include, for example, post-procedure infections.

Prerequisite: stable cornea

In a first step, a cross-linking is done in preparation. After healing, eyesight is unchanged compared to the condition before cross-linking. Six months after this surgery, we can then assess whether the cornea can be lasered or whether it should wait. 

Laser and CXL – simultaneously or sequentially?

We do the lasering only after cross-linking. The reason for this is that even very safe and successful cross-linking does not always work 100%: in 3 to 7% of cases, keratoconus progresses even after maximal cross-linking. In other cases, which are also very rare (0.5%), the cornea may flatten off strongly after cross-linking. Again, one is glad if not lasered at the same time.

Rather, it should be waited with the lasers until the cornea are stable.

Precise lasering

Just a few years ago, the basic prerequisite for a precise lasering of a cornea after cross-linking was missing: it was not known exactly how much corneal tissue after a CXL is removed by an excimer laser pulse. Is it just as much tissue as in a cornea without cross-linking? Or 20% less? Or 40% more?

Not knowing how high the ablation rate is means an inaccurate result. 

Our research

In a large study, our group has determined the ablation rate in corneas after CXL. The work was published in 2014 in the American Journal of Refractive Surgery. Since then, we know that in a cornea with CXL, 12% less tissue is removed per excimer laser pulse than in a cornea without CXL. This knowledge enables us to significantly increase the accuracy of the treatment.

Our results

In addition to the increase in visual acuity, it is above all the increase in image quality that represents a benefit for our patients. Unlike visual acuity, there is still no simple measure for the term “image quality” in ophthalmology.

Therefore, the increase in visual acuity is just one of the elements that improves. It is also important that an increase of more than 50% visual acuity can improve the three-dimensional vision (depth perception).

wfPRK-and-CXL-Case-2-pre
Before
wfPRK-and-CXL-Case-2-post
After

35-year-old man, 1 year after laser treatment.

Vision increased with glasses from 20% to 60%.

wfPRK-and-CXL-Case-3-pre
Before
wfPRK-and-CXL-Case-3-post
After

41-year-old man, 3 months after laser treatment.

Eyesight increased from 60% to 80% with glasses.

wfPRK-and-CXL-Case-4-pre
Before
wfPRK-and-CXL-Case-4-post
After

33 year old woman, 2 years after laser treatment.

Eyesight increased from 50% to 80% with glasses.

wfPRK-and-CXL-Case-5-pre
Before
wfPRK-and-CXL-Case-5-post
After

51 year old woman, 2 years after laser treatment.

Eyesight increases with glasses from 50% to 125%.

wfPRK-and-CXL-Case-6-pre
Before
wfPRK-and-CXL-Case-6-post
After

40-year-old woman, 1 year after laser treatment.

Eyesight increased from 40% to 50% with glasses.

wfPRK-and-CXL-Case-7-pre
Before
wfPRK-and-CXL-Case-7-post
After

28-year-old man, 3 months after laser treatment.

Eyesight increases with glasses from 40% to 60%.

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Augeninstitut ELZA
4.7
Based on 80 reviews
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Thomas S.
Thomas S.
09:37 07 Jul 21
My left eye had to be operated on because of a cataract. As I had an Artiflex lens implanted a few years ago, it had to... be removed first before a modern lens could be implanted to correct the cataract. Prof. Hafezi treated me in an very competent and friendly manner. I am very happy with the result.read more
Selma A. Rahim
Selma A. Rahim
19:45 02 Jul 21
Dr. Hafezi.. the KING OF CXL🤴
Gianluca Ricci
Gianluca Ricci
12:46 10 Apr 21
Great team and service!
rehaneyecare
rehaneyecare
05:36 08 Apr 21
Excellent surgeon
Steven H.A
Steven H.A
16:13 11 Jan 21
Prof. F. Hafezi s expertise is enormous and he has a very pleasant and calm nature which gives the patient... security.Thank youread more
Online Commande
Online Commande
09:19 05 Dec 20
Totally creepy, very arrogant Prof.He just want your money.It may explain, why this Prof. is not in the center of the... city of Zürich and why he has been thrown away from University of Geneva.read more
Elena Churilova
Elena Churilova
10:06 17 Nov 20
At the moment, 3 months have passed since the moment I made laser vision correction in this clinic. and I can say that... I am happy that I chose this particular clinic and Prof. F. Hafezi. The entire staff of the clinic is very friendly, treats patients with sympathy and patience if they are nervous before surgery (my big gratitude to Aida Alili for all support and patience). The doctor Hafezi and other doctors of the clinic are very professional and ready to explain to you as many times as you need. I can only recommend!read more
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Augeninstitut ELZA
4.7
Based on 80 reviews
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