PACK cross-linking in keratitis

UV light and Vitamin B2

The use of ultraviolet light and vitamin B2 (riboflavin) to sterilize surfaces and solutions is not new. This combination has been used for decades in medicine and the chemical industry. For example, the number of microbes in large Olympic swimming pools is often reduced with vitamin B2 and sunlight. In addition, the technology has been used for years to reduce the number of bacteria in blood transfusions. In addition, there was also the SODIS (Solar Disinfection) technology developed by ETH Zurich to reduce the burden of drinking water with microbes. Here, vitamin B2 is added to water in PET bottles and exposed to direct sunlight for several hours. After this treatment, bacteria, fungi and even viruses in the bottle are killed.

UV light and vitamin B2 are the components of the cross-linking of the cornea, which has been used since 2002 for the treatment of keratoconus and which we have co-developed significantly. The question then arose as to whether the method could possibly also be used for corneal infections.

Pioneered in Zurich: cross-linking for corneal infections

In 2006 and 2007, our group in Zurich treated the world’s first patients with this new method. Only patients who show no improvement after treatment with antibiotics were treated. The success was promising and the beginning of a branch of research that is becoming increasingly important.


PACK-Cross-Linking (PACK-CXL)

At the International Cross-Linking Congress in Zurich in 2014, Farhad and Nikki Hafezi proposed a new term to better describe cross-linking for infections: PACK-CXL (photoactivated chromophore for infectious keratitis). The proposal was accepted and has since been used for this new treatment method.



Reasons to use PACK-CXL

There are a number of reasons to use this new method:

  • Mixed infections:
    in many countries of the world, the corneal infections are not bacterial but mixed, that is caused by bacteria and fungi. Antibiotics alone do not help here. PACK cross-linking kills bacteria and fungi.
  • Therapeutic and diagnostic dilemma: at the beginning of an infection it is sometimes very difficult to assess whether the infection is caused by bacteria or fungi. Accordingly, it is difficult to select the appropriate therapy. PACK cross-linking simplifies the approach by simultaneously killing bacteria and fungi.
  • Financial burden: in many countries of the world, the corneal infection can not be successfully treated for financial reasons. The costs are less due to the medication than through the many doctor visits that are necessary. One-time PACK cross-linking reduces the total number of visits required by the doctor.

How does PACK-CXL work?

It works in three different ways:

1. It prevents microorganisms from multiplying by deactivating the genetic material,
2. It kills microorganisms directly by a very high oxidative stress and
3. It increases the resistance of the tissue to the inflammatory digestion.

1 Intercalation with DNA = stops replication

2 Oxidative stress

3 Increased resistance to digestion

PACK-CXL videos


Brazil’s top Ophthalmology magazine, Oftalmologica Em Foco, features ELZA’s Prof. Hafezi and Dr. Torres-Netto exploring the story of how CXL at the slit lamp is becoming a reality.
Farhad Hafezi was interviewed during ESCRS 2019, held in Paris, France, by Touch Medical Media on how CXL is performed at the slit lamp.

The ELZA Institute