Eyeworld

EW CORNEA March 2011 71 R esearch suggests that for at least one type of seri- ous eye infection, phototherapeutic keratec- tomy (PTK) rather than medicine is the cure. Researchers studied four cases of Acanthamoeba keratitis, finding that PTK is an ef- fective alternative when organisms are resistant to antibiotics. "When lesions are limited to about one third of the superficial corneal stromal layer, PTK could be the most beneficial option for treat- ing Acanthamoeba keratitis, resistant to medical amoebic therapy using chlorhexidine or polyhexamethyl- ene biguanide, because of direct re- moval of resistant amoebic cysts and better visual recovery without irreg- ular astigmatism," reported study co-author Tomoyuki Inoue, M.D., ophthalmology department, Osaka University Medical School, Osaka, Japan. The study was published on- line in June 2010 in Cornea. Clearly, further investigation be- yond four cases is warranted, and even PTK used as therapy in these cases caused some amount of con- cern involving corneal thinning after repeated attempts to eradicate the organisms. But, Dr. Inoue said, "because of rapid healing and better visual re- covery, PTK could be the most bene- ficial option for the treatment of Acanthamoeba keratitis resistant to medical amoebic therapy … espe- cially when the lesion is limited to the superficial corneal layer." Not just a last resort Dr. Inoue analyzed four eyes of four patients—46, 37, 22, and 14 years old—diagnosed with Acanthamoeba keratitis and treated with PTK. These patients were contact lens wearers, which was determined to be an un- derlying cause of the condition. "The medical regimens for all 4 patients included administration of topical 0.05% chlorhexidine diglu- conate hourly, 0.1% miconazole ni- trate hourly, 1% natamycin ointment 6 times daily, levofloxacin 4 times daily, oral itraconazole 200 mg daily, and/or corneal debride- ment once weekly," Dr. Inoue noted. "PTK was performed in the cases re- sistant to combined medical therapy after at least 1 week and in cases with an enlarged abscess that was limited to the superficial stroma." These amoebic lesions were dif- fuse in nature and took up a third of the superficial corneal stromal layer. "The interval from the onset to the start of medical treatment was 3.3 +/–1.5 weeks, and the interval from onset of therapy to PTK was 4.8 +/–2.4 weeks," Dr. Inoue re- ported. Total ablation depth was 253.8 +/–95.3 microns. by Matt Young EyeWorld Contributing Editor PTK—not medicine—can sometimes cure infections INAMURA II HYDRODISSECTION CANNULA, 25G – AE-7653 Unique Dual port cannula with a flow of 30º makes hydrodissection easy and complete in one pass. Sandblasted tip can be used for rotation of the nucleus. TAN DSAEK FORCEPS – AE-4226 Endothelium cell loss is reduced to a minimum by grasping the stromal part of the endothelium button with the specially designed jaws. Available in 23G and 25G. INAMURA SOFT NUCLEUS PRECHOPPER – AE-4189 Reduces phaco time up to 50%. Swan Prechopper easily splits soft nuclei completely and rotates nuclei in the capsular bag. Designed for soft nuclei, grades 1 & 2. Today's Precision...Tomorrow's Vision ASICO LLC 26 Plaza Drive • Westmont, IL 60559 • USA Phone: 630-986-8032 • Fax: 630-986-0065 Customer Service: 1-800-628-2879 www.asico.com • E-mail: info@asico.com © 2011 ASICO LLC Today's Precision...Tomorrow's Vision ® The more you know... TM Latest Innovations from ASICO Latest Innovations from ASICO AD89-11 Temporal marking is made precise with the help of the bubble level. Non-marking surface is minimized to provide better visibility. Specially designed blades easily transfer ink onto the eye. Designed to be used temporally on the right or left eye. 30° NUIJTS-LANE PRE-OP TORIC MARKER WITH BUBBLE – AE-2791TBL APAO BOOTH: 518 • ASCRS BOOTH: 2833-2825 LatestInnov_EyeWorld:Layout 1 2/10/11 3:07 PM Page 1 an individual's pre-surgical measure- ments." Although it needs further test- ing, this mathematical model may be useful as a jumping-off point to determine the IOL power that should be used in combined DSEK and phacoemulsification procedures. Meanwhile, other researchers have made important strides in un- derstanding the nature of hyperopic shift after DSEK. In September 2009, Vincenzo Scorcia, M.D., Casa di Cura Villa Serena, ophthalmology department, Forli, Italy, reported in Ophthalmol- ogy that changes in posterior corneal curvature are a possible cause of the hyperopic refractive shift found after Descemet's stripping automated en- dothelial keratoplasty (DSAEK), an- other name for DSEK. He found that this was a negligi- ble shift for patients who were cor- rected with spectacles after surgery but important for patients undergo- ing IOL surgery. "The difference in thickness be- tween center and periphery of the DSAEK graft induces a change in posterior corneal curvature, result- ing in a hyperopic shift that de- creases with time and is negligible for spectacle correction," Dr. Scorcia reported. "However, when perform- ing a triple procedure, intraocular lens selection should take into ac- count the refractive change induced by DSAEK." EW Editors' note: Dr. Hwang has no finan- cial interests related to the IOVS study. Dr. Scorcia has no financial interests re- lated to the Ophthalmology study. Contact information Hwang: richard.y.hwang@duke.edu Scorcia: vscorcia@libero.it Mathematical continued from page 70 continued on page 72

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