EyeWorld Asia-Pacific September 2012 Issue

September 2012 18 EWAP FEAturE Topography of crosslinking and Intacs Source: Peter S. Hersh, MD Doubling up by Enette Ngoei Senior EyeWorld Contributing Editor 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, MD, associate clinical professor of ophthalmology, New York University, New York, NY, USA, and director of Laser Vision, GR Institute, Athens, Greece, said that while crosslinking was efficient in stabilizing ectasia, visual rehabilitation was challenging. This was especially true in a large majority of patients who could not wear specialty lenses for keratoconus 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 PRK to normalize the highly irregular cornea with the WaveLight excimer laser (Alcon, Fort Worth, Texas, USA/Hünenberg, Switzerland), he said. By using this combined approach on the cornea—partial myopic 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 removal, he explained. While Dr. Kanellopoulos said the refractive result is a bit unpredictable, what is predictable is that the best corrected visual acuity in these patients is dramatically improved. In a 2009 study he and colleagues 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 appreciate the morbidity, the expense, and the very long visual rehabilitation 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-micron magnitude, a frugal approach as far as tissue removal, Dr. Kanellopoulos explained. The indication for this combined procedure, known as the Athens Protocol, is progressive keratoconus, Dr. Kanellopoulos said. Crosslinking and Intacs When looking at combined crosslinking procedures, it is important 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 contours and improve the topography of those patients who have keratoconus and corneal ectasia, said Peter S. Hersh, MD, director, Cornea and Laser Eye Institute, Teaneck, NJ, USA, who has been studying the combined use of corneal crosslinking and Intacs (Addition Technology, Des Plaines, Ill., USA). The purpose of Intacs is to provide 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 obtain 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 procedure and the crosslinking procedure be done concurrently or should it be done with the Intacs first and the crosslinking later?” Dr. Hersh said. Preliminary results of the study show no difference thus far between the two with regard to the outcome of corneal flattening and corneal stabilization, he said. Dr. Hersh said that over 90% of keratoconic patients in his studies so far are stabilized, although approximately 5% of them continue to progress despite the crosslinking. With regard to visual acuity, most patients remain stable and in fact, a number get better vision, he said, although a small percentage of patients can lose a small amount of visual acuity. With Intacs, some patients may complain of glare from optical reasons or because of infection or inflammation, and the Intacs would need to be removed. In his aforementioned study, though, there was no need for Intacs removal, he said.