The effect of cooled irrigation fluid on post-phacoemulsification dry eye and corneal endothelium parameters

CLINICAL RELEVANCE: Corneal oedema and dry eye symptoms following phacoemulsification are major determinants of early postoperative satisfaction. Strategies that protect the ocular surface and minimize endothelial stress during phacoemulsification are therefore of clinical importance. BACKGROUND: To evaluate the effect of using cooled Balanced Salt Solution as an irrigation fluid during phacoemulsification on postoperative dry eye findings and corneal endothelial function. METHOD: In this prospective study, Group 1 consisted of 114 cataract patients who underwent phacoemulsification with the use of cooled BSS (2.7 ± 0.1°C), whereas Group 2 comprised 115 patients who received room‑temperature BSS as the irrigation fluid. The presence of dry eye was evaluated preoperativelyand on postoperative day one, day three, week one, and month one using tear break-up time (TBUT), the Schirmer test, and corneal fluorescein staining scoring. Additionally, corneal endothelial parameters were evaluated using non-contact specular microscopy across five distinct corneal quadrants:central, superior, inferior, nasal, and temporal. RESULTS: On the first postoperative day, TBUT and Schirmer test values were significantly higher in Group 1, and the fluoresce in staining score was significantly lower (p < 0.05 for all). Similarly, on the third postoperative day, TBUT remained significantly higher and the staining score lower in Group 1 (p = 0.002 and p = 0.014, respectively). The staining scores in the central and superior corneal quadrants were significantly lower in Group 1 on the 1st and 3rd postoperative days (p < 0.001 for both). At postoperative days one and three, the reduction in endothelial cell density and in hexagonality observed in the superior corneal quadrant was significantly less in Group 1. Corneal thickness and coefficient of variation values in the superior quadrant were significantly lower in Group 1 (p < 0.05 for all). CONCLUSION: The use of cooled BSS during phacoemulsification may mitigate postoperative dry eye symptoms during the initial period when complaints are most pronounced, potentially contributing to a more comfortable postoperative course for patients.