[Influence of corneal thickness on intraocular pressure measurements following Descemet's stripping automated endothelial keratoplasty (DSAEK)]. / Einfluss der Hornhautdicke nach posteriorer lamellärer Keratoplastik (DSAEK) auf die Messung des Augeninnendrucks.

BACKGROUND: The aim of this study was to evaluate the effect of increased corneal thickness after Descemet's stripping automated endothelial keratoplasty (DSAEK) on intraocular pressure (IOP) measured by four different techniques. METHODS: In this study 30 eyes from 30 patients with successful DSAEK treatment (group 1) and 30 eyes of 30 healthy subjects (group 2) were enrolled. The IOP was measured with iCare, IOPen, Goldmann applanation tonometry (GAT) and dynamic contour tonometry (DCT) techniques. Central corneal thickness (CCT) was measured by ultrasonic pachymetry. These data were used for statistical analysis. RESULTS: The mean IOP measured by GAT, DCT, iCare and IOPen was 13.2, 16.1, 12.5 and 14.2 mmHg in group 1 and 13.4, 14.4, 14.4 and 13.3 mmHg in group 2, respectively. Correlations between IOP and CCT were not statistically significant in either group. CONCLUSION: The results of IOP measurements by the iCare, IOPen, GAT and DCT techniques seem to be unrelated to artificially thickened corneas after DSAEK. In spite of partially good correlation between the four techniques a direct exchange of the devices is not recommended on account of the wide dispersion of values.

[Complications after cosmetic iris implantation]. / Komplikationen nach kosmetischer Irisimplantation.

We report the case of a 37-year-old patient with ocular complications associated with the implantation of cosmetic iris implants. Implantation of silicone iris implants for the purpose of changing iris colour has been performed since 2004. Diaphragms are implanted in the anterior chamber. Up to now only little information exists about side effects of this method. In the literature severe ocular complications shortly after cosmetic iris implantation are reported in single cases. In our case 5 months after surgery optic nerve damage caused by elevated intraocular pressure (IOP) was diagnosed. Nuclear opacity of both lenses and a decreased number of corneal endothelial cells were observed at the first visit. Because of recurrent IOP elevation despite maximum antiglaucoma therapy, explantation of the iris implants was required. Damage to the trabecular meshwork, opacity of the lenses as well as the reduced number of endothelial cells are permanent and will probably lead to further complications like corneal decompensation and progressing glaucoma.

[New trends in tonometry]. / Neue Trends in der Tonometrie.

BACKGROUND: Though the knowledge about the risk of elevated intraocular pressure for pathogenesis for development and progress of glaucoma is more than 400 years old. It took another 300 years before by means of tonometry this elevation could be quantified. After discussion of the key words it is our aim to demonstrate the latest trends in tonometry, specifically by use of modern electronics for instrument design. MATERIALS: Goldmann was the founder of the "applanation tonometry", measuring the corelation of applanated area and applied force. Here, the next step was the development of instruments, measuring independent of position or gravity to allow application also at the lying patient. Electronic area detection was the next step to avoid examinor's error. Also important was the introduction of automatic UV-desinfection to avoid contamination of the other eye or other patients. Other tonometers control the force applied by an inductive method, which also allows application independent of position. Airpuff-tonometry uses completely different measuring principles - the resulting change of corneal curvature indicates the intraocular pressure. The impedance principle is applied even through the closed eye lid. The shock waves resulting shall be measured. Direct application of a surface sensor incorporated into a concave surface contact body shall allow direct measurement of intraocular pressure independent of corneal thickness, curvature, astigmatism. This method has been tried for more than 20 years. Also exposition of the eye to count waves of different frequency was an early attempt. Here also change of reflectivity is used to calculate intraocular pressure. CONCLUSIONS: Even after use of modern electronic technology the precision of many of these new devices does not lead to better results. This specifically is shown by modern calibration methods.