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Cross-linking extremely thin corneas

The original Dresden protocol allows CXL to be performed safely when the thickness of the cornea is 400 μm or higher. However, in advanced cases of keratoconus, pellucid marginal degeneration and post-LASIK ectasia, the cornea may be thinner.

One way to treat such a cornea nonetheless is the use of hypo-osmolar riboflavin. This special vitamin B2 causes the cornea to absorb water and swell. This technique was developed in 2007 and published in 2009 with Prof. Hafezi as first author. Since then, this application has become a global standard.

2008: The “Birth” of CXL in ultrathin corneas.

Zurich, Switzerland: A 26-year-old patient is being treated with epi-off CXL. After removal of the epithelium and application of “normal” iso-osmolar riboflavin, the corneal thickness is 325 microns; too little to do a safe CXL. In a second step, we used hypo-osmolar riboflavin. After 10 more minutes, the cornea had “swollen” to 407 microns, and the CXL could be performed safely.

The treatment of extremely thin corneas requires a lot of experience as many factors have to be considered – from how often the vitamin B2 is applied, to how long the speculum is left open. Our experience is one of the longest in the world and allows us to safely perform a CXL on thin corneas (and thicker corneas too!).


The future

A number of strategies have been developed to treat very thin corneas since 2009. ELZA’s Medical Director, Farhad Hafezi, has helped to reivew these techniques (see posts below), including contact lens-assisted CXL (CACXL) and the Epithelial Island Technique. Which technique is chosen must be carefully considered on a case-by-case basis.

In addition, the research group led by Professor Hafezi is in charge of developing new techniques that are tailored to the individual corneal thickness. In the future it will be possible to treat corneas of less than 300 μm using CXL, without swelling the cornea first.

the sub400 protocol individualized CXL

CXL for ultra-thin corneas: the sub400 protocol webinar

"CXL for ultra-thin corneas: the sub400 protocol" shows a revolutionary new protocol to treat ultra-thin keratoconic corneas down to 215
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MEACO: ELZA goes to Jordan

I was honoured to be invited to give a series of talks during this year's MEACO congress, held in the
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Cross-Linking in thin corneas: simple, personal and more precise

Keratoconus is the progressive thinning of the cornea, and corneal cross-linking (CXL) can successfully treat it. The application of riboflavin
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Algorithm predicts CXL effect

A new algorithm to predict the Cross-Linking effect

New algorithm predicts CXL effect and might help to treat keratoconus corneas thinner than 400 µm. Algorithm predicts CXL effect:
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ELZA speaks at USC Roski Eye Institute Refractive Symposium 2017

USC Roski Eye Institute Refractive Symposium 2017 with ELZA Founder Prof. Hafezi. Farhad Hafezi speaks on treating ultra-thin keratoconus corneas
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How to cross-link extremely thin corneas

January 2017. Eye World Interview with Dr. Sabine Kling and Prof. Farhad Hafezi. The interview shows how thin corneas will
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New research on thin corneas from Zurich might be the clue to cross-linking very thin keratoconus corneas in the future

Journal of Refractive Surgery. Zurich, Switzerland. A new study by the research group of Prof. Farhad Hafezi may open new alleys
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Cross-Linking thin corneas

Ocular Surgery News Europe. Specialists intrigued by new approaches to cross-linking thin corneas. Read here.
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Effect of hydration on corneal biomechanics

Journal of Refractive Surgery. Read here.
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Limitation of Cross-Linking in extremely thin corneas

Cornea. Description and discussion of failure of CXL technology in extremely thin corneas. Read here.
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Collagen cross-linking in thin corneas

Journal of Cataract and Refractive Surgery. The study that had introduced hypotonic/hypoosmolaric riboflavin for thin corneas. Read here.
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