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ICRS implantation should precede, not follow, corneal collagen cross-linking
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 Tamer El-Raggal |
ISTANBUL, Turkey — Femtosecond channel dissection and intracorneal ring segment implantation should be performed before or concurrent with corneal collagen cross-linking to avoid increased laser energy and consequent haze formation, according to a study.
The study was conducted at the Magrabi Eye Hospital in Cairo, Egypt. In 15 eyes of 11 patients with keratoconus grades 1 through 3, channel dissection for intracorneal ring segment (ICRS) implantation was performed 6 months after collagen cross-linking treatment, using the IntraLase FS-60 (Abbott Medical Optics). Eyes were randomized to three groups, in which laser power settings of 1.5 mJ, 1.6 mJ and 1.7 mJ were used. Five non-cross-linked keratoconus eyes were used as controls.
The degree of difficulty of ICRS insertion was judged subjectively, and eyes were examined postoperatively for corneal haze development.
"In the group with the lowest power setting, intracorneal channel creation was incomplete and we needed to finish it with mechanical dissection. More elevated power settings allowed the femtosecond laser to perform complete channels, but this resulted in increased corneal reaction and haze development," Tamer El-Raggal, MD, said at the winter meeting of the European Society of Cataract and Refractive Surgeons.
Collagen cross-linking stiffens not only the more superficial 300 µm of the stroma, but also the deeper stroma, Dr. El-Raggal said. Tissue bridges, which are a common problem in tunnel creation with femtosecond laser, create an even stronger resistance in these conditions.
Haze was transient, and completely resolved within 6 weeks without further complications. However, to entirely avoid laser power modification and haze, ICRS implantation should precede, not follow, cross-linking, Dr. El-Raggal said.
- Disclosure: Dr. El-Raggal has no direct financial interest in the products discussed in this article, nor is he a paid consultant for any companies mentioned.