Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Review
. 2016 Apr 19:3:11.
doi: 10.1186/s40662-016-0042-x. eCollection 2016.

PACK-CXL: Corneal cross-linking in infectious keratitis

David Tabibian  1 , Cosimo Mazzotta  2 , Farhad Hafezi  3
Affiliations
Review

PACK-CXL: Corneal cross-linking in infectious keratitis

David Tabibian et al. Eye Vis (Lond). .

Abstract

Background: Corneal cross-linking (CXL) using ultraviolet light-A (UV-A) and riboflavin is a technique developed in the 1990's to treat corneal ectatic disorders such as keratoconus. It soon became the new gold standard in multiple countries around the world to halt the progression of this disorder, with good long-term outcomes in keratometry reading and visual acuity. The original Dresden treatment protocol was also later on used to stabilize iatrogenic corneal ectasia appearing after laser-assisted in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK). CXL efficiently strengthened the cornea but was also shown to kill most of the keratocytes within the corneal stroma, later on repopulated by those cells.

Review: Ultraviolet-light has long been known for its microbicidal effect, and thus CXL postulated to be able to sterilize the cornea from infectious pathogens. This cytotoxic effect led to the first clinical trials using CXL to treat advanced infectious melting corneal keratitis. Patients treated with this technique showed, in the majority of cases, a stabilization of the melting process and were able to avoid emergent à chaud keratoplasty. Following those primary favorable results, CXL was used to treat beginning bacterial keratitis as a first-line treatment without any adjunctive antibiotics with positive results for most patients. In order to distinguish the use of CXL for infectious keratitis treatment from its use for corneal ectatic disorders, a new term was proposed at the 9th CXL congress in Dublin to rename its use in infections as photoactivated chromophore for infectious keratitis -corneal collagen cross-linking (PACK-CXL).

Conclusion: PACK-CXL is now more frequently used to treat infections from various infectious origins. The original Dresden protocol is still used for this purpose. Careful modifications of this protocol could improve the efficiency of this technique in specific clinical situations regarding certain types of pathogens.

Keywords: CXL; Corneal cross-linking; Corneal ulcer; Infectious Keratitis; Keratoconus; PACK-CXL; Riboflavin; Ultraviolet light A.

PubMed Disclaimer

Figures

Fig. 1
Fig. 1
Pre- and post-treatment peripheral infectious keratitis. a Anterior segment photography of a patient with early peripheral infectious keratitis (arrow). b Anterior segment OCT of the lesion. c Anterior segment photography of the same patient 7 days after PACK-CXL (9 mW/cm2 irradiance for 10 min) with resolution of the peripheral infectious keratitis (arrow). d Anterior segment OCT of the lesion at day 7 after PACK-CXL
See this image and copyright information in PMC

References

    1. Wollensak G, Spoerl E, Seiler T. Riboflavin/ultraviolet-a-induced collagen crosslinking for the treatment of keratoconus. Am J Ophthalmol. 2003;135(5):620–7. doi: 10.1016/S0002-9394(02)02220-1. - DOI - PubMed
    1. Wollensak G, Spoerl E, Seiler T. Stress–strain measurements of human and porcine corneas after riboflavin-ultraviolet-A-induced cross-linking. J Cataract Refract Surg. 2003;29(9):1780–5. doi: 10.1016/S0886-3350(03)00407-3. - DOI - PubMed
    1. Hafezi F, Kanellopoulos J, Wiltfang R, Seiler T. Corneal collagen crosslinking with riboflavin and ultraviolet A to treat induced keratectasia after laser in situ keratomileusis. J Cataract Refract Surg. 2007;33(12):2035–40. doi: 10.1016/j.jcrs.2007.07.028. - DOI - PubMed
    1. Richoz O, Mavrakanas N, Pajic B, Hafezi F. Corneal collagen cross-linking for ectasia after LASIK and photorefractive keratectomy: long-term results. Ophthalmology. 2013;120(7):1354–9. doi: 10.1016/j.ophtha.2012.12.027. - DOI - PubMed
    1. Ehlers N, Hjortdal J, Nielsen K, Søndergaard A. Riboflavin-UVA treatment in the management of edema and nonhealing ulcers of the cornea. J Refract Surg. 2009;25(9):S803–6. doi: 10.3928/1081597X-20090813-08. - DOI - PubMed

LinkOut - more resources