EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
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EW CORNEA 50 January 2016 by Michelle Dalton EyeWorld Contributing Writer cylinder decrease and infero-supe- rior ratio improvement with single segments, he said. "In my early experience with ICRS, I used to choose either single or double segments based on compa- ny-based nomograms for a particular device, but I have leaned toward single-ICRS use, with good results, in order to theoretically only induce corneal flattening in the location of greatest steepness, which usually is located inferotemporally, for most cones, and not flatten the superior cornea, which could potentially lead to further distortion," he said. Intacs SK is a newer design that has an inner diameter of 6 mm, oval cross section, and two different thicknesses (0.40 and 0.45 mm), designed for those with more severe keratoconus. "In theory, the smaller the inner diameter of the device, the greater the flattening effect should be, and based on that logic, the Intacs SK, positioned in the location of the cone, has become my go-to single device when considering an ICRS," Dr. Perez said. The primary reason to continue implanting ICRS, Dr. Jackson said, is to flatten the cornea enough and reduce the myopia enough to enable contact lens fitting. "CXL will be my first line of treatment because the ultimate goal is to prevent disease progression," he said. "Implanting Intacs with CXL will not only stop the disease but make the lens fit easier. When Although keratoconus has recognized stages, these are mostly reliant upon "keratometric values and pachymetry, but those two pa- rameters are not always parallel with one another," Dr. Kilic said, and with the use of more sophisticated topography, she does not always abide by the staging to determine treatment. "Patient selection is still very important," she said. "If you per- form ICRS on someone with very good visual acuity, they may end up with an irregular astigmatism and visual loss. But if there is progression and high refraction, performing CXL and ICRS together is helpful. ICRS is also a kind of refractive surgery." Using ICRS can help improve corneal shape, and most patients will achieve some visual improve- ment, but they are not risk-free, said William Trattler, MD, Center for Eye Care Excellence, Miami. "Some studies have reported up to 10% of enrolled eyes needing removal of the Intacs segment." Intacs, Intacs SK, CXL, and others When using ICRS, the decision between using single or double seg- ments can depend on several factors, Dr. Perez said, including recommen- dations from a particular device company, personal surgeon prefer- ences, or a particular nomogram. Some studies, particularly Sharma and Yeung, 1,2 describe better uncor- rected and corrected vision, greater enough, he might even consider the Visian ICL (STAAR Surgical, Monro- via, Calif.), for reduction of the high myopic component typically seen, but only if the cornea and refraction are stable; he will not consider a toric ICL once FDA approved due to difficulty in knowing the correct axis to place the ICL in these patients. Intacs will have an excellent place in conjunction with CXL for lower myopic correction when needed, he said. Even though intracorneal ring segments can create biomechanical changes on the cornea, "they do not have an effect on disease progres- sion, therefore, if progression is sus- pected, a CXL procedure needs to be performed in combination with the use of these devices," said Mauricio Perez, MD, Salvador Hospital/Clini- ca Las Condes, Santiago, Chile. "Our protocol with ICRS is to perform a same-day CXL in order to try to lock the biomechanical and flattening effect of the ICRS and at the same time, attempt to stop progression of the disease. The only cases in which we do not perform same-day CXL while using ICRS are in previously crosslinked corneas." Aylin Kilic, MD, consultant, Dunya Eye Hospital, Istanbul, Turkey, has "extensive experience" with ICRS but has not seen the same improvement after implantation as reported in the literature. She will, however, implant Intacs in higher levels of keratoconus, "or I'll com- bine CXL and Intacs." Outside the U.S., corneal crosslinking and intracorneal ring segments for higher levels of keratoconus are viable treatments T reating keratoconus in the U.S. will likely involve contact lenses, following by intracorneal ring segments (ICRS) and/or corneal transplant with either penetrating keratoplasty or deep anterior lamel- lar keratoplasty if vision correction is not possible with non-invasive means. Outside the U.S., however, surgeons are also able to combine these procedures with corneal cross- linking (CXL). At press time there were no commercially approved CXL devices in the U.S. Mitchell A. Jackson, MD, founder and CEO, JacksonEye, Lake Villa, Ill., has tapered the use of Intacs (Addition Technology, Lombard, Ill.) "because contact lens fitting has become much more ad- vanced. Most patients who received Intacs for keratoconus were going to need contact lenses anyhow; if you catch keratoconus early enough you can perform CXL, which has better outcomes than Intacs in terms of truly halting the progression of the disease. Some surgeons are combin- ing the procedures, which is what I'll likely do once CXL is approved in the U.S." If the patient is young Treating keratoconus Device focus develop treatments that can stimu- late and/or regenerate LSCs." Some cases will require autolo- gous topical serum drops, but they were not necessary in the study. The PROSE scleral lens is sometimes useful because it provides a microen- vironment that promotes a healthy limbal niche. In his lab, Dr. Djalilian is further investigating LSCD. "Our latest research is on finding ways to help support and nourish the LSCs. Right now, the only way we can provide that is through serum tears, but that is not specific enough. We are developing a treatment in our lab that consists of supportive factors produced by stem cells. In experi- mental models, we have shown that this can improve LSCD," he said. EW Reference 1. Kim BY, et al. Medically reversible limbal stem cell disease: clinical features and management strategies. Ophthalmology. 2014;121:2053–2058. Editors' note: Dr. Djalilian has no financial interests related to this article. Contact information Djalilian: adjalili@uic.edu Limbal stem cell disease: A treatment primer 1. Stop the offending agent(s) such as a soft contact lens and benzalkonium chloride preserved drops. 2. Aggressively treat dry eyes and meibomian gland disease. 3. Add anti-inflammatory therapy—typically steroids followed by cyclosporine emulsion for long-term use. 4. If necessary, add serum tears and use scleral lenses in recalcitrant cases. Source: Ali Djalilian, MD Finding continued from page 49