ECO-CAIRS strategy offers optimization, ease of implantation for allogenic ring segments
Key takeaways:
- Femto-CAIRS have advantages over PMMA ring segments for keratoconus but may be difficult to insert.
- With ECO-CAIRS, high-fluence cross-linking makes the segments stiffer and easier to implant.
ATHENS, Greece — Cross-linking CAIRS before implantation makes insertion easier, enhances the flattening effect and eliminates potential sources of infection, according to a speaker.
At the ESCRS winter meeting, Farhad Hafezi, MD, explained to Healio the novel ECO-CAIRS (extracorporeal optimization of corneal allogenic intrastromal ring segments) strategy.
Femto-CAIRS are made of corneal tissue and are therefore better tolerated than PMMA rings. However, because the tissue is floppy, it is not easy to insert, particularly for beginners, he said. Shady Awwad, MD, proposed dehydrating the segments before implantation, but as soon as they are put into the cornea and they get in contact with fluid, they swell, and the surgeon has to try to push them forward into the tunnel.
Extracorporeal optimization consists of applying cross-linking to the segments after they are cut with the femtosecond laser, outside of the body, “where nothing can be harmed by UV light,” Hafezi said.
High fluence of 30 J to 60 J is used in this procedure to make the tissue as stiff as a piece of plastic. Once inserted, it does not swell immediately, giving the surgeon time to complete the procedure.
“It becomes super flat, and only after a week or two it expands, so you can make it flat into the tunnel, and then the volume increases. This drives the flattening effect,” Hafezi said.
There is an added advantage, he said, because corneal tissue is not tested for keratoconus in the eye bank, and there is a risk of implanting a keratoconus segment into an eye in which the surgeon wants to counteract the effects of keratoconus.
“By doing this ultra-strong cross-linking, we kill everything living in this ring segment. It is basically only a skeleton, a scaffold of collagen, which is ideal,” Hafezi said. “We are trying to establish a nomogram based on the volume and stiffness of the ring segments” to obtain a customized effect for each cornea.
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Hafezi F. Extracorporeal optimization of corneal allogenic intrastromal ring segments (ECO-CAIRS) using ultra high-fluence corneal cross-linking. Presented at: ESCRS winter meeting; Feb. 28 - March 2; Athens, Greece.
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