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Editors Selection IGR 17-4
(Laser) Surgical treatment: Laser iridotomy and corneopathy
Comment by Robert Ritch & Yaniv Barkana on:
19890 Argon laser iridotomy-induced bullous keratopathy a growing problem in Japan, Ang LP; Higashihara H; Sotozono C et al., British Journal of Ophthalmology, 2007; 91: 1613-1615
Ang et al. (1476) describe a strangely high number of eyes that underwent penetrating keratoplasty (PK) due to what they determined to be 'argon laser iridotomy (ALI) induced bullous keratopathy (BK)' in one medical center in Japan. This was determined to be the primary indication in 39 of 195 (20%) PK surgeries. Regrettably, the authors do not provide a scientifically-valid basis for their published results and so these cannot be accepted as reported. In this retrospective work, the authors reviewed the records of all patients that underwent PK over a four-year period and extracted pertinent data. However, none of this data is reported, and the authors do not explain how they determined that the BK was indeed 'ALI-induced'. We do not know how many of these eyes had previously undergone cataract (and/or other intraocular) surgery, especially a complicated one, or non-surgical trauma. We do not know if and how the authors excluded other causes for BK such as Fuchs' dystrophy. We do not know the laser parameters used during ALI in these eyes. A meaningful interpretation of the reported results cannot be made when these fundamental data are absent. It is especially peculiar that analysis that included these data was not provided by the authors nor demanded by the journal reviewers, when the reported finding is so extraordinary and, in the same paper, the authors note that PK was rarely attributed to ALI in one medical center in Singapore, where angle closure is more prevalent, and never in one center in the UK. While ALI has been performed for decades, associated long-term corneal edema has been reported in only a few cases, some of which were clearly diagnosed with corneal endothelial dystrophy. ALI remains an extremely safe procedure. One of us (RR) has done thousands of ALIs since 1978 and can remember only one patient with corneal breakdown. In 1986, on a lecture tour of Japan, I introduced short duration, low power burns (0.01-0.02 second and 500-600 mW) for dark brown irides and performed a few for demonstration purposes. Nevertheless, even today, I find ophthalmologists, not just in Japan, using settings from the early days of ALI, such as 0.1-0.2 second and 1500 mW, settings which cause endothelial and epithelial burns and extensive inflammation and require a far greater number of burns for penetraton because of concomitant charring of the iris stromal surface.
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