Tear crystallization patterns in dogs with evaporative dry eye disease treated with hyaluronic acid and tacrolimus

This study investigated the effects of three treatment protocols for evaporative dry eye disease (EDED) in dogs by analyzing tear crystallization patterns using the Rolando and Masmali scales. Fifty-four dogs with EDED were randomly assigned to three treatment groups: G1 (0.30% sodium hyaluronate + 0.03% tacrolimus twice daily), G2 (0.30% sodium hyaluronate four times a day), and G3 (0.30% sodium hyaluronate twice daily). Tears were collected using Schirmer strips, centrifuged (25830 g for 10 min), and analyzed using polarized light microscopy on days 0, 15 and 45. Crystallization patterns were classified based on the Rolando and Masmali scales. G1 and G3 showed a predominance of Rolando type II and Masmali grade 2 patterns. G2 exhibited a higher frequency of type III patterns (58.3%) at baseline and showed a significant improvement over time: Rolando (D0 vs. D45, P < 0.001), Masmali (D0 vs. D15, P = 0.021; D0 vs. D45, P < 0.001). G3 also showed significant improvement on the Masmali scale (D0 vs. D45, P = 0.005; D15 vs. D45, P = 0.021). Tear ferning proved useful for monitoring therapeutic response in canine EDED, with improvements noted following hyaluronic acid administration two to four times daily.