Rabinowitz presented Intacs (Addition Technology Inc., Des Planes, Ill.) as an important alternative to the corneal transplant for keratoconus at The Cornea Society's Federated Scientific Session during the annual meeting of the American Academy of Ophthalmology, Anaheim, Calif.

Corneal transplants have historically helped manage the keratoconus condition, but Rabinowitz is convinced Intacs is a safer alternative in select patients.

	Three patterns of Intacs Source: Yaron Rabinowitz, M.D.

Research results

In his retrospective study, Rabinowitz reviewed charts of all patients at Cedars-Sinai that had Intacs surgery for keratoconus with at least one year follow up. The patients were contact lens intolerant with a clear visual axis.

Of 12 eyes identified, nine experienced improved vision and are now contact lens tolerant. The patients also experienced a mean of three lines improved uncorrected acuity and a mean 2.4 lines in improved best-corrected acuity. Sphere was reduced a mean 3 D and astigmatism a mean 1.43 D.

"I think they were great results," Rabinowitz said. "Patients avoided a transplant and can see pretty well."

However, one patient had Intacs removed due to erosion of the segment and one had Intacs explanted from both eyes because of continuing visual changes one year postoperatively.

Regarding the eroded segment, Rabinowitz said, "That was really due to my inexperience - it was one of the first eyes I ever did - and I put the segments too superficially and it eroded, so I decided to remove the Intacs."

Rabinowitz is not the first to report on Intacs for keratoconus.

Colin was the first to study this issue in Europe, where ophthalmologists are trying to avoid corneal transplants if possible because there is a shortage of corneal tissue, Rabinowitz said.

"What Dr. Colin showed was that when you put these rings in keratoconus, because the tissue in keratoconus is a lot more malleable and thinner, you actually get a much bigger effect and you can maybe correct up to 5 D or 6 D of myopia," Rabinowitz said. "When you fit them with contact lenses, not only were they more contact lens tolerant, they actually saw better with contacts than they saw before."

However, Rabinowitz said Colin's and Siganos' keratoconus patients were only mild to moderate, where in his study the patients had more severe keratoconus albeit with a clear visual axis, and he still got promising results - an important distinction.

Rabinowitz said he also performed his own study using only segments approved by the FDA, which was not the case with Colin's study.

Patients and patient expectations

Keratoconus patients with corneas less than 350 mm thick and those with central corneal scarring are not good candidates for Intacs, Rabinowitz said.

Even patients that expect to be independent of glasses or contact lenses following the procedure are poor candidates, he said.

While in many cases, Rabinowitz noted enhanced vision for Intacs patients in his study, "patients expectations should be limited to improved contact lens tolerance," he said. "With keratoconus patients, even though they have improved vision, they're still left with a certain amount of myopia and astigmatism - that never gets truly eliminated."

A new modification

Rabinowitz said his Intacs procedure includes placing a suction device on the eye; making channels in the cornea with two blades - first to the right, then to the left; and placing the plastic Intacs segments into the channels.

While the channels in the study participants were made with microkeratomes, Rabinowitz said he has recently used the IntraLase (IntraLase Corp., Irvine, Calif.) femtosecond laser to create them.

"IntraLase can create the channels a lot more elegantly than the blade, makes it a much simpler procedure and a lot less risky," Rabinowitz said. He said he is currently conducting research on using the IntraLase for this procedure.

In addition, a common side effect of blade usage is the creation of epithelial defects, which are virtually eliminated by the femtosecond laser, he said. The laser is also much more accurate than the blade in creating channel depth, he said.

Editors' note: Rabinowitz has no financial interests in Addition Technology or IntraLase.