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A.U. Hafner, B. Seitz, A. Langenbucher, G.O. Naumann; Phototherapeutic Keratectomy (o-PTK) for Recurrent Granular and Lattice Dystrophy After Corneal Transplantation Using the 193 nm Excimer Laser- Long-Term Results of 20 Consecutive Procedures . Invest. Ophthalmol. Vis. Sci. 2003;44(13):3871.
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Purpose: Phototherapeutic keratectomy (PTK) may be applied to treat recurrent epithelial defects (e-PTK) or superficial corneal opacities (o-PTK). The purpose of this prospective study was to investigate morphological and functional long-term results after o-PTK in recurrent granular and lattice dystrophy on corneal grafts. Patients and Methods: Between 02/1989 and 11/2002, 20 out of 317 PTKs were performed because of recurrent granular or lattice dystrophy after corneal transplantation. Patients were divided into two groups: group 1 included 14 PTKs performed because of recurrent granular dystrophy on the corneal graft, group 2 6 PTKs because of recurrent lattice dystrophy on the corneal graft. The intended laser ablation after epithelial debridement and pannectomy varied from 10-80 µm (group 1) and from 20-80 µm (group 2). We used the slit-scanning-mode of the Zeiss-Meditec laser with a repetition rate of 20/s or 25/s, a mean pulse energy of 15.7 mJ (group 1), 22.2 mJ (group 2) and a mean pulse rate of 2027 (231-6370) (group 1), 1964 (815-3806) (group 2). Results: Mean follow-up was 3.0+/-2.4 (max. 6.7) years (group 1) and 2.9+/-2.8 (max. 6.9) years (group 2). Best-corrected visual acuity improved from 0.3+/-0.2 to 0.5+/-0.1 (group 1) and from 0.25+/-0.2 to 0.4+/-0.2 (group 2). Median spherical equivalent did not change significantly in group 1 (–0.89 diopters (D) preoperatively, –0.95 D postoperatively) and decreased from 0.5 D to 0.0 D in group 2. Mean central keratometric power decreased from 44.2+/-4.8 D to 42.5+/-4.9 D (group 1) and did not change significantly in group 2 (41.3+/-1.2 D pre-, 41.6+/-2.6 D postoperatively). In group 1 we noticed 4 recurrences (28%) after a mean period of 2.4 (2.0–3.3) years, but no recurrence in group 2. Conclusion: In superficial opacities, caused by recurrent granular or lattice dystrophy after corneal transplantation, o-PTK using the 193 nm excimer laser usually results in a moderate improvement of best-corrected visual acuity without significant changes of spherical equivalent and central corneal power. Thus, a repeat penetrating keratoplasty can be avoided or at least delayed in most cases.
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