EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/220233
November 2013 Corneal crosslinking EW FEATURE 43 Peak efforts in keratoconus by Maxine Lipner EyeWorld Senior Contributing Writer Using crosslinking with adjunctive treatments C ollagen crosslinking has become a valuable tool for practitioners in corralling keratoconus threatening a patient's vision. Sometimes, however, crosslinking alone is not enough and adjunctive measures are needed. From use of intracorneal ring segments to topographic PRK or even PTK, here's what you need to know about these adjunctive procedures. Selecting adjunctive treatments has to be individualized, said Judy YF Ku, MD, honorary senior lecturer, University of Auckland, New Zealand, and in private practice, Brisbane, Australia. "I think crosslinking by itself should be for those who have relatively good best corrected vision still, with mild to moderate keratoconus on topography, and with documented evidence of progression," she said. "But in some of the patients, crosslinking may not be enough." flattening effect on the central cornea by the fact that it's positioned closer to the visual axis and the corneal center," Dr. Ku said. Treatment is individualized with either single or double Intacs used depending on the cone type. "If you have an inferiorly decentered cone then by using paired segments it can cause excessive flattening of the superior cornea, which you don't need," Dr. Ku said. "So we use single segments in those who have decentered cones, asymmetric astigmatism and a flat or normal superior cornea on topography." However, those who have a central cone receive a pair of Intacs segments. Sheraz Daya, MD, medical director, Centre for Sight, London, augments his crosslinking treatments with the Ferrara Ring (Ferrara Ophthalmics, Belo Horizonte, Brazil). First he crosslinks patients, a step that he finds may be enough to successfully allow them to wear glasses. He then waits three to six months to see whether this step is enough to arrest the progression of keratoconus and get patients in spectacles or not. "If they can't get into a pair of spectacles, it is because their cornea is abnormally shaped, because they AT A GLANCE • Some practitioners use Intacs in conjunction with collagen crosslinking to help regularize the cornea in keratoconus cases. • Some find the short arcs of the Ferrara Ring make these a natural for correcting astigmatism in crosslinked patients. • With adjunctive topographicguided ablations, nearly half of one center's patients attained 20/40 uncorrected vision at one year. continued on page 44 Intracorneal ring segments In addition to crosslinking, Dr. Ku uses intracorneal ring segments for those who are contact lens intolerant, who also have a clear central cornea with no significant scarring. Dr. Ku prefers to do this on the same day as crosslinking rather than sequentially. "For patients it's just one surgical procedure," she pointed out, adding that the intracorneal ring segments may have a greater flattening effect on the cornea before this is stiffened by crosslinking months prior. In her practice they use Intacs (Addition Technology, Des Plaines, Ill.), an adjunct that she tends to limit to those with best corrected vision of 20/60 or better. Those with poorer vision, she finds, often do not benefit from this. "Traditionally we'll use it in mild to moderate keratoconus only," Dr. Ku said. "But with the newer segments, such as the Intacs SK, we found that it's becoming useful in those with more advanced keratoconus." The Intacs SK has an oval cross section and a smaller inner diameter of 6.0 mm, compared to 6.8 mm with the standard Intacs. "It's thought that with this modification it exerts a greater Preoperative topography of a 20-year-old patient with keratoconus revealed an inferior cone. His UDVA was 20/125 and BDVA was 20/20 with +2.00/–4.25 x 90. Ten days following same-day collagen crosslinking, PTK, and a single inferior Intacs segment, his UDVA improved significantly (20/30-1). Topography revealed reduction in inferior cone steepness. At one year, the improvement in his UDVA persisted (20/25-2), and he was functioning well with spectacle correction (plano/–2.00 x 93 = 20/20). Source: Judy YF Ku, MD, and David S. Rootman, MD