A novel porcine dry eye model system (pDEM) with simulated lacrimation/blinking system: Preliminary findings on system variability and effect of corneal drying

Purpose. To investigate inter- and intra-system variations and the effect of cornea! drying using a recently developed pDEM. Methods. pDEM was used to simulate "normal" and "dry eye" conditions using two "lacrimation-blink" intervals (20 s and 60 s). Corneas were examined/graded with sodium fluorescein before and after the experiment. At the end of each experiment, corneas were assessed by trypan blue exclusion technique. Two duplicated pDEM systems were set up and tested to investigate reproducibility. Results. There was no significant difference in the results produced by the two pDEM systems. In the eyes under "normal" condition, there was no significant increase in the fluorescein grading. However, in eyes under "dry eye" condition, fluorescein staining increased and the number of non-viable cells in the central cornea increased. Conclusions. This novel pDEM system provides a useful assessment tool for the study of causative factors and new treatment strategies for dry eye syndrome.