Abstract
Purpose: :
To determine how the Moria microkeratome measurements of donor cap central corneal thickness (CCT) compare to those obtained by mechanical micrometer and Visante Anterior Segment Ocular Coherence Tomography (Visante AS-OCT).
Methods: :
Sixty-four donor corneas used in anterior lamellar keratoplasty (ALK) and/or Descemet's stripping automated endothelial keratoplasty (DSAEK) procedures by three Cornea specialists at Houston Eye Associates from April 2007 to January 2008 were included in this study. After lamellar dissection in a Moria artificial chamber using a 300 or 350 µm microkeratome head, the CCT of the donor caps was measured by a Mitutoyo mechanical micrometer and Visante AS-OCT prior to transplantation. Pachymetry data by these two methods was then compared using linear regression analysis and paired Student T-tests.
Results: :
Mean donor cap CCT measurements by micrometer were 414 ± 6.64 µm and 513 ± 2.92 µm using the Moria 300 and 350 µm microkeratomes, respectively. Similar measurements were obtained when these donor caps were again measured by Visante AS-OCT (408 ± 7.27 µm and 519 ± 4.45 µm). On regression analysis, the correlation coefficient between the mechanical micrometer and Visante AS-OCT was 0.886. The paired student T-test showed no significant difference among the means of these two samples. Bland-Altman analysis of the mechanical micrometer and Visante AS-OCT data also showed excellent agreement between these two measurement modalities.
Conclusions: :
The Moria microkeratome consistently underestimates donor cap CCT as measured by both the Visante AS-OCT and mechanical micrometer, with important implications for lamellar keratoplasty procedures. The latter may afford an accurate, yet more cost-effective, alternative to the Visante AS-OCT for measurement of donor cap CCT.
Keywords: transplantation • cornea: clinical science • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)