Eyeworld

March 2011 "However, intraoperative obser- vation of the corneal infectious focus during PTK with diffuse illumi- nation was not as good as with a slit lamp, making determination of the end point of PTK difficult," Dr. Inoue reported. "The residual amoe- bic lesions worsened after PTK; therefore, additional ablation was needed in cases 1 and 4." Illumination-assisted PTK was found to be helpful. "Illumination- assisted PTK using sclerotic scatter- ing illumination during the procedure was reported to be an op- tion for achieving better visibility for opacified tissues and avoiding excessive ablation," Dr. Inoue re- ported. "In cases 2 and 3, this illumi- nation technique was performed and no additional ablation was re- quired." Case 4, involving the 14-year- old male, had significant scarring. "Case 4 had corneal stromal scarring that should be considered a possible complication in cases in which a large amount of tissue is removed," Dr. Inoue reported. Nonetheless, after the last PTK, in all cases clinical symptoms re- solved, and medications were re- duced. Best corrected visual acuity (BCVA) also improved in all cases. Pre-op, BCVA ranged from 20/80 to 20/2000 while post-op, BCVA was 20/16 to 20/25. PTK pros and cons Dr. Inoue suggested that PTK works because it directly removes amoebic cysts, inflammatory cells, and necrotic tissues. Among other ad- vantages, it also allows for better vi- sual recovery without the irregular astigmatism that might result after other surgical procedures. It's much less invasive, for instance, than PK. "Most candidates are myopic, so hyperopia after PTK is less problem- atic than in the usual patients who undergo PTK," Dr. Inoue reported. "However, the limited optimal pe- riod during which to perform PTK and inevitable corneal thinning should be considered." John D. Sheppard, M.D., pro- fessor of ophthalmology, microbiol- ogy, and immunology, Eastern Virginia Medical School, Norfolk, Va., called the study an "outstand- ing contribution" to medical litera- ture. "Infection control is all about decreasing the number of organ- isms," Dr. Sheppard said, suggesting PTK can do that by cutting infected layers away neatly and smoothly. Physical scraping wouldn't be able to reach the same layers, he said. Hence, physicians have relied on antimicrobial agents as well. But Dr. Sheppard advocates using as few antimicrobial agents as possible, and fewer micro-organisms after PTK would lead to less need for drug usage. "These are strong drugs that sting, produce redness and ep- ithelial toxicity, and are expensive," Dr. Sheppard said. He suggested that in some cases, ophthalmologists could use PTK to reduce refractive error while also re- ducing the micro-organisms present. EW Editors' note: Dr. Inoue has no finan- cial interests related to this study. Dr. Sheppard has no financial interests re- lated to his comments. Contact information Inoue: tinoue@ophthal.med.osaka-u.ac.jp Sheppard: 757-622-2200, docshep@hotmail.com WWW.GEUDER.COM rincon.de PRECISE CORNEA MARKING FOR PREMIUM TORIC IOLs T MARK · FLEXIBLE: Variable use either on slit lamp or with hand-held pendulum instrument · PRECISE: Highly accurate pre-operative marking of the fi nal torus position · EASY: Fast and reliable handling due to simple degree setting and easily readable scale VISIT GEUDER AT THE ASCRS BOOTH NO. 2925 SAN DIEGO RZ_0353_Anz_EyeWorld_Tomark_End.indd 1 20.01.11 11:28 PTK continued from page 71 A patient with Salzmann's nodular degeneration. Left: The pre-op appearance of the eye. Right: The clinical appearance of the eye 10 weeks after PTK with mitomycin C. New research finds that PTK may also be useful to treat Acanthamoeba keratitis Source: Brandon Ayres, M.D.

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