EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/78788
46 EW SECONDARY FEATURE February 2011 Crosslinking August 2012 Doubling up by Enette Ngoei EyeWorld Contributing Writer Can combining corneal crosslinking with refractive surgery improve outcomes for keratoconus and ectasia patients? EyeWorld finds out D escribing his early experience with corneal crosslinking in patients with keratoconus and ectasia, A. John Kanellopoulos, M.D., associate clinical professor of ophthalmology, New York University, New York, and director of Laser Vision, GR Insti- tute, Athens, Greece, said that while crosslinking was efficient in stabiliz- ing ectasia, visual rehabilitation was challenging. This was especially true in a large majority of patients who could not wear specialty lenses for kerato- conus such as rigid gas permeable lenses. "The ectasia was stabilized, but the visual rehabilitation remained a significant problem. So we employed several techniques after crosslinking to address the visual rehabilitation," said Dr. Kanellopoulos, who has been performing crosslinking for about 10 years. Crosslinking and PRK One of these adjunctive procedures is a topography-guided partial photorefractive keratectomy (PRK) to normalize the highly irregular cornea with the WaveLight excimer A topography of crosslinking and Intacs Source: Peter S. Hersh, M.D. laser (Alcon, Fort Worth, Texas), he said. By using this combined ap- proach on the cornea—partial my- opic treatment, partial hyperopic treatment—Dr. Kanellopoulos and colleagues were able to achieve in the central part of the cornea more spherical lenticular behavior than before with very little tissue re- moval, he explained. While Dr. Kanellopoulos said the refractive result is a bit unpre- dictable, what is predictable is that the best corrected visual acuity in these patients is dramatically im- proved. In a 2009 study he and col- leagues published, on average, the majority of patients who underwent this combined procedure jumped from a best corrected visual acuity of around 20/70 and 20/60 to 20/40 or better, Dr. Kanellopoulos said. The drawbacks include a long rehabilitation period of anywhere from 2-10 weeks when the corneal surface is healing and the potential risk of thinning these corneas, he said. "We did share this problematic decision when we started treating these eyes, but the alternative for most of the patients was a corneal transplant approach; as a corneal transplant surgeon, I heavily appre- ciate the morbidity, the expense, and the very long visual rehabilita- tion of these patients in order to try this approach as a last attempt before transplantation," he said. In addition, the actual benefits of stability and visual rehabilitation far outweigh the potential risk of thinning these corneas, and with regard to the thinnest part of the cornea, which is usually the point of ectasia, the total tissue removal is in the 30 or 40 µ magnitude, a frugal approach as far as tissue removal, Dr. Kanellopoulos explained. The indication for this com- bined procedure, known as the Athens Protocol, is progressive kera- toconus, Dr. Kanellopoulos said. Crosslinking and Intacs When looking at combined crosslinking procedures, it is impor- tant to remember that the goal of crosslinking is to make the cornea biomechanically more stable, while the goal of adjunctive procedures is to further improve the corneal con- tours and improve the topography of those patients who have kerato- conus and corneal ectasia, said Peter S. Hersh, M.D., director, Cornea and Laser Eye Institute, Teaneck, N.J., who has been studying the com- bined use of corneal crosslinking and Intacs (Addition Technology, Des Plaines, Ill.). The purpose of Intacs is to pro- vide direct structural support with the goal of modifying the corneal topography to make the cornea both flatter and more symmetric, he said; when these two procedures are used in combination, the hope is to ob- tain the different beneficial effects of each of them in combination. In a single-center, prospective, randomized clinical trial with two randomized groups, one with 22 eyes that underwent corneal crosslinking and Intacs implantation concurrently and another with 21 eyes that had Intacs implanted first followed by corneal crosslinking 3 months later, Dr. Hersh and colleagues have been looking at whether the procedures can be safely combined with a good result and which of them is the proper sequencing. "That is, should the Intacs pro- cedure and the crosslinking proce- dure be done concurrently or should it be done with the Intacs first and the crosslinking later?" Dr. Hersh said. A topography of crosslinking and PRK Source: A. John Kanellopoulos, M.D. continued on page 48