Eyeworld

47 EW FEATURE January 2019 • Crosslinking playbook Editors' note: Dr. Majmudar has finan- cial interests with Alcon (Fort Worth, Texas), Bausch + Lomb, and CXL Ophthalmics (Encinitas, California). Dr. Talley Rostov has financial interests with Allergan and Bausch + Lomb. Dr. Trattler has financial interests with Allergan, Bausch + Lomb, CXL USA, Avedro, and Oculus. Contact information Majmudar: pamajmudar@yahoo.com Talley Rostov: atalleyrostov@nweyes.com Trattler: wtrattler@gmail.com know that there is a higher inci- dence of progression and that they should be more closely monitored in the first 3 to 5 years after the procedure. "Progression after ker- atoconus is a controversial topic, and there is no good metric that is widely adopted as the sine qua non of keratoconus progression. At this time, we are using a combination of change (steepening) in keratometric indices coupled with loss of best corrected visual acuity as an indica- tor of progression," he said. EW Reference 1. Seiler TG, et al. Customized corneal cross-linking: one-year results. Am J Ophthal- mol. 2016;166:14–21. equivalent refractive error, best corrected visual acuity, topography, and tomography. If using a Penta- cam (Oculus, Wetzlar, Germany), two screens Dr. Trattler recommends are the Belin ABCD screen, which evaluates changes over time, as well as difference maps. "Evaluating changes over time with the Sagittal view difference map is quite helpful. Progression is noted when there is steepening in the steep area and flattening in the flat area," he said. Dr. Talley Rostov said she will retreat if there is more than 1 D of consistent change. However, her retreatment rate is only 3% to 5%. In patients who are 15 to 25 years old, Dr. Majmudar lets them Monitoring progression "Typically, once patients are deter- mined to be stable at 6 months or 1 year, annual exams are adequate to monitor for progression," Dr. Trattler said. "Of course, if patients note changes in vision in either eye, they should return earlier for repeat testing." Although CXL strengthens the cornea, some patients have such weak corneas that they require two CXL procedures, Dr. Trattler said. Progression may not be evident for 1 to 3 years because the changes can occur very slowly over time, he ex- plained. When monitoring for pro- gression, surgeons should measure uncorrected visual acuity, spherical CXL continued from page 46 AT A GLANCE • CXL alone is appropriate for the earliest topographic changes with minimal thinning. • TCAT PRK and CXL can treat progressive keratoconus, pellucid marginal degeneration, and ectasia after laser vision correction. • Intacs can benefit CXL patients with insufficient residual stromal bed for TCAT and is superior to TCAT for pellucid marginal degeneration. • Some patients treated sequentially with adjunct CXL treatments obtain better results than those undergoing combined procedures. by Rich Daly EyeWorld Contributing Writer Some surgeons have found adjunctive therapies can work well with corneal crosslinking W hen surgeons consider adjunctive treatments to corneal crosslink- ing (CXL), the severi- ty of corneal thinning and the presence of comorbidities are key factors. George Waring IV, MD, found- er and medical director, Waring Vision Institute, Mount Pleasant, South Carolina, emphasized the need to assess such corneal cases individually. Crosslinking alone is beneficial for strengthening the cornea and improving its biomechanics. To sur- gically address irregular astigmatism in such eyes, Dr. Waring uses either a single or a coupled asymmetric ring. To correct myopia, implantable contact lenses can benefit patients, while scleral or hybrid specialty lenses can treat irregular astigma- tism or myopia. "Typically, if it is a mild cone, meaning the earliest topographic changes with minimal thinning with usually minimally adequate visual acuity, then we would recom- mend crosslinking alone to stabilize the cone and prevent inflamma- tion," Dr. Waring said. Adjunctive treatments to crosslinking emerge In moderate or severe cases, Dr. Waring typically recommends a single- or double-inch corneal ring segment implant and crosslinking. "There may be a role for an implantable contact lens for myopia and for the regular component of astigmatism because now there's a contact lens available. Also there may be a role, particularly in the more severe cases, for a specialty contact lens on top of that," Dr. Waring said. For Raymond Stein, MD, med- ical director, Bochner Eye Institute, Toronto, Canada, the combination of topography-guided custom abla- tion treatment (TCAT) PRK and CXL has become the preferred treatment for progressive keratoconus, pellucid marginal degeneration, and ectasia after laser vision correction. "This allows for a highly cus- tomized treatment in which steep areas of the cornea are flattened and flat areas are steepened," Dr. Stein said. "This reduces irregular astigma- tism. We can add a small refractive component, but the main goal is to improve best corrected spectacle acuity and not uncorrected visual acuity." Dr. Stein tries to limit tissue re- moval to 50 microns. He limits the use of Intacs (Addition Technology, Lombard, Illinois) to cases in which the central cornea is less than 430 microns. That approach leaves 99% of such patients of his treated with TCAT PRK and CXL. Contraindications to TCAT PRK include significant central corneal scarring or cases with excellent un- corrected acuity in which the corne- al steepening is primarily below the pupillary zone. Similarly, Eric Donnenfeld MD, clinical professor of ophthalmology, New York University, New York, pre- fers to perform TCAT over Intacs be- cause the results of TCAT—in good candidates—are generally better and there is no risk of late rejection, extrusion, or infection, which can occur with Intacs. In addition to topographic abnormalities, Dr. Donnenfeld can treat myopia with laser correction. When a patient is not a good candidate for an excimer laser abla- tion, Dr. Donnenfeld will use Intacs. For example, Intacs can benefit patients with insufficient residual stromal bed, and Intacs is superior to TCAT for pellucid marginal de- generation, as long as the peripheral cornea has a pachymetry of at least 400 microns. "When performing TCAT on patients with peripheral steepening such as pellucid the tissue ablation is in the periphery, and this results in a hyperopic treatment pattern that may make the patient signifi- cantly more myopic than they were to begin with," Dr. Donnenfeld said. continued on page 48 "I prefer to treat the topographic ab- normality with TCAT and to reduce or eliminate the residual myopia as long as the stromal bed is sufficient to remove additional tissue." Whether to combine Dr. Waring said U.S. surgeons have slowly begun to combine tran- sepithelial treatment or PRK with crosslinking. However, he has seen patients treated with adjunct treatments obtain better results with sequen- tial, rather than simultaneous,

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