[The use of intracorneal rings in penetrating keratoplasty].
BACKGROUND
The visual rehabilitation after penetrating keratoplasty (PKP) is affected by postoperative corneal astigmatism. Up to now studies were focused on different trephine systems as well as the suture techniques. A new option for reducing postoperative corneal astigmatism could be the implantation of an intracorneal ring.


METHODS
Over a period of 2 years we implanted in 20 patients, who were suffering from keratoconus, Fuchs' dystrophy or bullous keratopathy, an 8-mm cobalt-molybdenum-titanium intracorneal ring in a prospective clinical trial. We used the guided trephine system (GTS) for preparation and a 10-0 nylon double running suture. The mean follow-up period was 16.2 months. A control group of 20 additional patients who underwent PKP was randomized. Topographic astigmatism as well as the spherical equivalent was evaluated after 1, 3, 6 and 12 months, respectively.


RESULTS
Although a lower topographic astigmatism in the intracorneal ring group was reached 12 months postoperatively (3.0 dptr., SD 1.2 versus 4.0 dptr., SD 1.8) no statistical significance was found. The spherical equivalent in that group was lower during the complete evaluation period with a hyperopization in both groups as well. We did not see any immunological reactions caused by the ring.


CONCLUSIONS
Whether the intracorneal ring could be a useful addition to PKP is not yet clear. Therefore more patients need to be enrolled and further studies established.
Martin-Luther-Universität-Halle-Wittenberg, Klinik und Poliklinik für Augenheilkunde, Halle. dirkehrich@hotmail.com
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Ehrich
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Duncker
D000497:Alloys; D001251:Astigmatism / Q000517:prevention & control*; D003035:Cobalt; D003316:Corneal Diseases / Q000601:surgery*; D005500:Follow-Up Studies; D005642:Fuchs' Endothelial Dystrophy / Q000601:surgery*; D006801:Humans; D007640:Keratoconus / Q000601:surgery*; D015948:Keratoplasty, Penetrating / Q000379:methods* / Q000534:rehabilitation; D008982:Molybdenum; D010043:Outcome and Process Assessment, Health Care; D011183:Postoperative Complications / Q000517:prevention & control*; D011446:Prospective Studies; D011474:Prosthesis Design; D019919:Prosthesis Implantation; D012029:Refraction, Ocular; D013536:Suture Techniques; D014025:Titanium; D014792:Visual Acuity / Q000502:physiology
D000497:Alloys; D003035:Cobalt; D008982:Molybdenum; D014025:Titanium