Abstract

SA.09.11

Relation of trabecular meshwork outflow facility, tonometry and corneal thickness following descemet stripping endothelial keratoplasty (DSEK)

Katharina Weller, Jan Darius Unterlauft, Franz Grehn, Gerd Geerling
Universitäts-Augenklinik Würzburg

Objective
Increased intraocular pressure (IOP) is a frequent complication of penetrating keratoplasty and can be due to reduced trabecular meshwork outflow facility. Descemet stripping endothelial keratoplasty (DSEK) is a new lamellar technique for replacing pathological corneal endothelium and may be associated with a lower risk of postoperative IOP rise. In a prospective clinical study we studied IOP and outflow facility before and after DSEK.
Methods
In 13 eyes of 13 patients before, 1 day and 6 weeks, as well as 3, 6 and 12 months after DSEK IOP was measured using Goldmann applanation tonometry (GAT) and dynamic contour tonometry (DCT). Trabecular meshwork outflow facility was assessed by impression tonography with the Schioetz tonometer. Central corneal thickness (CCT) was measured by Haag Streit Pachymeter.
Results
IOP increased significantly from preoperatively 13.5 ± 3.3 mmHg measured with GAT (DCT: 14.7 ± 3.2 mmHg) to 16.3 ± 5.2 mmHg (DCT: 17.2 ± 4.6 mmHg) at 3 months and 15.3 ± 3.7 mmHg (DCT: 15.6 ± 4.1 mmHg) at 1 year after surgery (p=0.04). Outflow facility (C-value) increased significantly from 0.20 ± 0.03 preoperatively to 0.24 ± 0,04 at 3 months (p=0.0008) and 0.28 ± 0.05 (mm3/ΔmmHg/min) at 1 year (p=0.0005) post surgery. The mean CCT decreased from 647 ± 60 μm preoperatively to 586 ± 59 μm at 1 year (p=0.04).
Conclusions
Although DSEK results in an improved outflow facility, IOP as measured by GAT and DCT are increased during the first postoperative year. This paradox finding could be due to a progressive reduction of corneal oedema postoperatively, which is likely to result in an increased corneal rigidity. This in turn could simultaneously lead to increased IOP readings in transcorneal measurements and improved outflow facility due to increased transmission of force in transcorneal measurements.

Copyright: 2009 Porstmann Kongresse GmbH. All rights reserved. Impressum, Disclaimer.