Comparison of Corneal Endothelial Imaging Techniques by Specular Microscopy in Unsedated Healthy Dogs

OBJECTIVE: To compare unsedated noncontact specular microscopy imaging techniques for the canine corneal endothelium and identify the most effective technique. ANIMALS STUDIED: Nineteen eyes of 10 systemically healthy, staff-owned dogs with clinically normal corneas were studied. PROCEDURE: Six imaging groups were divided according to the different techniques used in all eyes: central focusing, with (CP) or without (CN) induction of an indirect pupillary light reflex (PLR); peripheral focusing with (PP) or without (PN) an indirect PLR; PP with application of a contact lens (CL); and gaze fixation with a treat (GF). The success rates, imaging times, and endothelial cell indices were compared. RESULTS: Success rates differed significantly among the techniques, with PP and CL achieving significantly higher success rates than CN. When only successful images were analyzed, the mean imaging time showed no statistically significant differences between the groups. In the sensitivity analysis, PP required significantly shorter imaging times than CN and PN. The Endothelial cell indices (cell count, endothelial density, and hexagonality) did not differ significantly among the techniques. CONCLUSIONS: Peripheral focusing combined with the induction of an indirect PLR (PP) achieved significantly higher success rates and shorter imaging times than other techniques, suggesting that this technique provides the most reliable and efficient approach for evaluating the canine corneal endothelium with noncontact specular microscopy under unsedated conditions.