EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
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39 EW CORNEA January 2019 Contact information Seitz: berthold.seitz@uks.de times greater for those who had lost two or more lines after ectasia. 3 "This study suggests that we keep in mind that patients who did not have visual loss from post-LASIK ectasia will have a greater risk of visual loss after the implantation of a ring segment," Dr. Seitz said. He explained that ICRS acts as placeholder between the loose collagen lamellae in the eyes of patients with keratectasia. "The arc shortening effect is proportional to the thickness of the ICRS and the optical zone size. The peripheral cor- nea at the site of the ICRS is 'moved' forward, thus flattening the central part of the cornea," he said. Indications for ICRS include moderate keratectasia (when it is "too early" for keratoplasty), contact lens intolerance, centrally clear cor- nea (no scars), steep K value below 62 D, corneal thickness at least 400 µm at the implantation site, and realistic expectations. Contraindica- tions for ICRS are advanced keratec- tasia grade IV, severe atopy, corneal hydrops, herpetic keratitis, and collagen, vascular, and autoimmune disease. "Post-LASIK corneal ectasia is one of the most troublesome complications after LASIK," Dr. Seitz said. "Its incidence has been report- ed to be between 0.04% and 0.6%. It can occur several months or even years after laser surgery. Risk factors include abnormal preoperative corneal topography, low residual stromal bed thickness, young pa- tient age, thin preoperative corneal thickness, and higher attempted refractive correction." According to his study out- comes, eyes with post-LASIK ker- atectasia benefited from Intacs SK implantation, improving both cor- rected and uncorrected visual acuity. Ectasia also seemed to be limited in these patients. EW References 1. El-Husseiny M, et al. Intracorneal ring segments to treat keratectasia – interim re- sults and potential complications. Klin Monbl Augenheilkd. 2016;233:722–6. 2. Alio JL, et al. Intrastromal corneal ring segments: how successful is the surgical treatment of keratoconus? Middle East Afr J Ophthalmol. 2014;21:3–9. 3. Brenner LF, et al. Indications for intrastro- mal corneal ring segments in ectasia after laser in situ keratomileusis. J Cataract Refract Surg. 2012;38:2117–24. Editors' note: Dr. Seitz has no financial interests related to his comments.