Eyeworld

EW FEATURE 44 Crosslinking playbook • January 2019 AT A GLANCE • Noting a patient's history of eye rubbing, symptoms, and the patient's current method of correction is important in the crosslinking decision-making process. • The FDA-approved crosslinking protocol requires corneal thickness of 400 microns. • Patient age is also an important factor. Younger patients may progress quickly and should be followed closely. by Ellen Stodola EyeWorld Senior Staff Writer/Digital Editor is too steep (usually above 70 D)." There is little benefit in crosslinking in these instances, he said. On exam, Dr. Randleman doc- uments the patient's symptoms, the method of current correction, and how long the patient has kept the same/similar visual correction. Eye rubbing history is also important, and he asks how the patient rubs his or her eyes. "I often demonstrate the technique of eye rubbing using the knuckle (not in my eye) and see if that resonates with the patient or the family," he said. "One may also see patients using the heel of their hand to vigorously rub." Dr. Randleman said he also wants to see the anterior curvature, regional corneal thickness, and epithelial thickness as determined by OCT. He uses topography and regional corneal thickness, either through Scheimpflug tomography or OCT. "I also always check for scissoring in retinoscopy for mild/ borderline cases," he said. "I have found this test to be as sensitive for early disease as topography." Crosslinking is indicated for pa- tients with progressive keratoconus and those with corneal ectasia fol- lowing refractive surgery, Dr. Rajpal said. "There are many findings that can suggest progression of keratoco- nus, therefore, we try to look at the patient as a whole rather than use a single indicator of progression," he said. "Changes that we document include increasing keratometry, decreasing pachymetry, changes Surgeons discuss preop factors T here are a number of preoperative consider- ations a surgeon may need to weigh when choosing crosslinking. These include evaluating the findings and different diagnostics as well as considering patient age, thickness of the cornea, and more. J. Bradley Randleman, MD, professor of ophthalmology, director of cornea, external disease, and refractive surgery, and medical director, USC Roski Eye Institute Beverly Hills, and Rajesh Rajpal, MD, chief medical officer, Avedro, Waltham, Massachusetts, and founder, See Clearly Vision Group, McLean, Virginia, discussed some of these considerations and im- portant patient factors that go into the decision of when to perform crosslinking. Recommending crosslinking Dr. Randleman thinks that subjec- tive findings are just as important as objective criteria in determining progression. Worsening vision with current correction and inability to achieve reasonable correction with the current strategy (i.e., a patient who has been wearing glasses is no longer able to use them, the current contact lens prescription no longer works well, or best corrected night vision is worsening significantly) indicate keratoconus progression, assuming there are no other issues, he said. Dr. Randleman noted that it may be too late to crosslink when the cornea "becomes severely thinned or scarred, or the cornea in visual quality, and/or increasing refraction (sphere/cylinder)." Dr. Rajpal noted that there are different findings that may indicate the need for further work up, such as increasing astigmatism or change in astigmatic axis, anisometropia, scissoring reflex on retinoscopy, or unexplained loss of BCVA. "We remind optometrists and general ophthalmologists in our area to be aware of the early warning signs of keratoconus and to send these patients in for baseline topographic evaluation," Dr. Rajpal said. Crosslinking is intended to slow or stop the progression of kerato- conus, he said, so early diagnosis is important as is treating patients as soon as it's indicated. "Progression can lead to loss of BCVA or de- creased contact lens tolerance that is not always reversible, and ideally, we want to catch these patients be- fore vision is lost," Dr. Rajpal said. When crosslinking is not recommended Generally, Dr. Rajpal said he does not perform crosslinking in a pa- tient scheduled to undergo either a penetrating keratoplasty (PK) or deep anterior lamellar keratoplasty (DALK) because in both cases, the majority of the central corneal stro- ma will be removed where the cross- links would be formed. "Recurrent keratoconus after a graft may be seen in the peripheral host cornea, however, reintroduction of mechan- ical stresses (such as vigorous eye rubbing) may also be implicated," he said. "The impact of crosslinking to the peripheral host cornea prior to a graft is an interesting area for clinical study." Dr. Randleman said that he would not recommend crosslinking prior to doing a planned DALK in a patient with advanced keratoconus. "Crosslinking has the most impact on the central cornea, so crosslink- ing will have little benefit prior to a planned DALK," he said. "Some surgeons avoid crosslinking cases where they strongly anticipate per- forming DALK as crosslinking has been reported to make obtaining a bubble more difficult." Younger patients Patients younger than 18 have particularly aggressive keratoconus, Dr. Randleman said, and when they present with any signs, they are like- ly to progress quickly. The consider- ation would be timing of treatment, he said, especially since parents may be motivated to postpone treatment for months due to school. "I highly encourage pediatric patients to have treatment as soon as possible as progression typically occurs in this group even in 1–2 months," he said. "That said, progression can occur at any age or stage of disease, so I fol- low all keratoconic patients closely until both the patient and I are con- vinced they are not progressing." Dr. Rajpal said that patients diagnosed at a younger age tend to show more rapid progression, Important considerations prior to crosslinking A difference map showing improvement after crosslinking in a patient in their mid 50s (a little older than the typical crosslinking patient) Source: J. Bradley Randleman, MD

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