OCT 2013

EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.

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62 EW CORNEA October 2013 Corneal crosslinking: The importance of screening and counseling in keratoconus patients by Arthur B. Cummings, MB ChB, FCS(SA), MMed (Ophth), FRCS(Edin) I t seems straightforward—performing corneal crosslinking in a contact lens intolerant patient with progressive keratoconus. But the odds of success can be reduced without a thorough preoperative screening, followed by careful management postoperatively. This is currently (with epitheliumoff techniques) an invasive procedure, where patients can sometimes struggle for months after treatment, so it's important to get your indications right. Appropriate indications for treatment In our practice, there have been two indications where we consider corneal crosslinking. The first is in younger patients (late teens to early 30s) who were showing signs of progression, i.e., the corneal steepness was increasing by >1 D over a 12 month period and the vision was decreasing by one line or more of BCVA over the same period. The second was for keratoconus patients that had been managed with an RGP (rigid gas permeable) contact lens, but had become intolerant of the lenses. In these patients, the next step was typically a corneal transplant if their best spectacle corrected vision was unsatisfactory or less than 6/24 (0.25). What we have found is that corneal crosslinking in these eyes restores the ability to wear RGP lenses again, postponing the need for a transplant. In this group of failed RGP wearers, not a single patient has required a corneal transplant following CXL at the clinic to date. We have treated at least 20 eyes for this indication to date. The UV-X 2000 device is being used here to apply accelerated CXL over 10 minutes at 9 mW in the center of the cornea and 12 mW in the periphery thanks to the optimized beam profile. Source: Arthur B. Cummings, MB ChB, FCS(SA), MMed (Ophth), FRCS(Edin) Following the 6th International Congress of Corneal Crosslinking held in Milan in January 2011, we've added a third indication. In keratoconic patients who are 27 years or younger, the consensus is that they receive a corneal crosslinking treatment—even if the eye has not yet shown signs of progression. In addition, crosslinking can be performed in eyes with pellucid marginal degeneration, peripheral melting diseases, as well as in recurrent keratoconus after corneal graft and post-LASIK ectasia. Crosslinking with isotonic riboflavin is contraindicated in eyes where the corneal pachymetry is less than 400 μm (without epithelium), eyes with epithelial healing disor- Clinical situation Decision Patient with signs of keratoconus or PMD (age 27 years or older) Observe progression by screening the patient; treatment is indicated in case of contact lens intolerance, loss of vision or increased corneal steepness or thinning Patient with signs of keratoconus or PMD (age below 27 years) Treatment is indicated Table 1 ders (e.g., MDF), nuclear rheumatic disorders and herpes keratitis (UV can activate herpes). In addition, crosslinking should not be performed during pregnancy. In eyes where the cornea is thinner than 400 μm, CXL can be performed with the use of hypotonic riboflavin. We routinely measure the pachymetry intraoperatively at 3 minute intervals for AXL (accelerated CXL over 10 minutes) and 5 minute intervals for CXL (standard 30 minute procedure) and then use hypotonic riboflavin if the cornea needs swelling. Appropriate counseling For patients who know that they have keratoconus and know that it's getting worse, they are far more inclined to want treatment as soon as possible so that the progression can be stopped. With these patients, it's usually only necessary to see them once and then they schedule the corneal crosslinking procedure. If the patient is coming to us with a new diagnosis of keratoconus, we first show them a video about keratoconus and the treatment options. We counsel the patient to get a second opinion and to wait six months to see how the disease evolves before making any decisions about treatment. But, particularly in younger patients, they will push to have the crosslinking treatment as soon as possible, fearing that their vision will decline rapidly during this waiting period. However, if the disease does progress that much in a sixmonth period, the odds are high that this patient may not be a particularly good candidate for corneal crosslinking due to the fact that this is a particularly aggressive form. Our experience, as well as that of others, is that CXL does not work particularly well on very advanced cases where the cornea is very steep (e.g., > 65 D). The other thing to consider when screening patients is that most keratoconus patients tend to have above-average intelligence and can be slightly obsessive compulsive. This means that they tend to really worry about the condition and spend time researching and reading about keratoconus. They need to be carefully guided through the decision-making process, as well as postoperatively in order to manage expectations. There is no doubt that the use of corneal crosslinking can dramatically improve the quality of life of keratoconus patients by reducing anxiety, while protecting their cornea, but it's vital to remember that the vision of these patients is at stake when we perform this procedure. Inappropriate patient selection or inadequate counseling can result in poor outcomes. But following these indications, allowing the patient to weigh the options, as well as using a clinically validated treatment protocol should result in stabilizing the cornea. EW Editors' note: Dr. Cummings is medical director of the Wellington Eye Clinic and consultant ophthalmologist at the UPMC Beacon Hospital, Dublin. He has no financial interests related to this article. Contact information Cummings: +353 1 2930470, abc@wellingtoneyeclinic.com

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