Abstract
Purpose: :
To compare human donor sectioned corneal thickness measurements made by non-contact optical coherence tomography (OCT) and contact ultrasound (US) pachymetry.
Methods: :
Post-mortem corneas were dissected from 10 donor globes - and were preserved in Optisol-GS (B&L, Rochester, NY). The corneas were then mounted on a microkeratome system (Moria, France) and were sectioned using a 300 micron head (119 to 182 hours post harvest time, 152 ± 22 hours). After resection and while still mounted on the artificial anterior chamber, the central thickness of each cornea was measured using a conventional US pachymeter (Advent Pachymeter, Accutome, PA). Each Descemet-Stripping Automated Endothelial Keratoplasty (DSAEK) section was then transferred into a vial containing Optisol-GS at room temperature and the vial was positioned in front of the Visante OCT using a special adaptor (Abeamed, Miami FL) and the central thickness of the DSAEK section was measured. The measured thicknesses obtained with OCT and US were compared.
Results: :
The mean US and OCT measured thickness was 226 ± 75 µm and 247 ± 76 µm respectively. The difference in measured sectioned thickness (OCT - US) was 21 ± 18 µm (p < 0.007). The two systems provide thicknesses that are highly correlated (p < 0.0001). After more than 100 hours of post harvest storage, linear regression of the DSAEK section central thickness indicates a significant correlation with post-mortem time (p < 0.003), increasing at a rate of 3 ± 2 µm per hour.
Conclusions: :
Non-contact Visante OCT yields slightly larger measurements of DSAEK donor thickness than US pachymetry, which required pressure on the tissue to obtain a measurement; however, the two systems are significantly correlated. OCT cannot contaminate tissues and therefore has this advantage over US pachymetry.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • cornea: basic science