Accuracy of corneal trephination depth using the Moria single-use adjustable depth vacuum trephine system

BACKGROUND The Moria single-use adjustable depth trephine is a device that allows a goal trephination depth to be set prior to the surgical procedure. METHODS Eleven fresh human cadaveric eyes were trephined using 8.0 mm Moria single-use adjustable vacuum trephines. Prior to trephination, the average corneal pachymetry in the peripheral 7-10 mm range was obtained using anterior segment optical coherence tomography. The trephination depth was set to 80% of that value. Light microscopy was used to image anteroposterior cross-sections of each corneal specimen. Digital protractor software was used to evaluate the trephination angle, depth, and length. All adequately processed specimens were included in the analysis. In addition, trephination angle data from a previous publication by Moshirfar et al were used as a comparison with those of this study. RESULTS Trephination analysis of depth compared with pachymetry revealed a mean of 83.7%±6.53% (95% confidence interval 79.8-87.6). Maximum and minimum trephined depths were 95.35% and 71.3%, respectively. Trephination depth compared with angular corneal thickness yielded a mean of 66.2%±4.79% (95% confidence interval 63.0-69.4). Maximum and minimum depths were 73.7% and 59.7%, respectively. Analysis of trephination angle yielded a mean of 130.2±3.57 degrees (95% confidence interval 127.8-132.61). Maximum and minimum angles were 135.5 degrees and 126 degrees, respectively. The standard deviation of the trephination angle of the Moria trephine was found to be significantly less than that of Hessburg-Barron and Hanna trephines calculated in the previous study. CONCLUSION The Moria adjustable vacuum trephine is an accurate method of trephination when a specific depth is desired. Further investigation is needed to determine the relevance of this in relation to deep anterior lamellar keratoplasty.