Evaluation of the Protective Effect of Mannitol-Containing Ophthalmic Viscosurgical Devices on Corneal Endothelial Cells During Phacoemulsification in Patients with Low Endothelial Cell Density

Purpose: To evaluate the safety and efficacy of mannitol-containing ophthalmic viscosurgical devices (OVDs) in protecting corneal endothelial cells during phacoemulsification cataract surgery in patients with low preoperative endothelial cell density (ECD) ranging from 1000 to 2000 cells/mm². Methods: This randomized controlled trial was conducted at Saigon Vinh Eye Hospital from October 2024 to May 2025. Patients with cataracts and low ECD (1000–2000 cells/mm²) undergoing phacoemulsification were randomly assigned to one of three groups based on the type of OVD used: (Group A) 2% sodium hyaluronate (SH) + 0.5% mannitol, (Group B) 1.4% sodium hyaluronate alone, and (Group C) 2.4% hydroxypropyl methylcellulose (HPMC). Endothelial cell density was measured preoperatively and at one week, one month, and three months postoperatively. Results: One week postoperatively, the group receiving OVD containing SH 2% and mannitol 0.5% showed significantly lower endothelial cell loss and better endothelial morphology than the SH 1.4% and HPMC 2.4% groups. Group A had the highest cell density (1443 ± 222 cells/mm²; p < 0.042), lowest coefficient of variation CV% (39.2 ± 9.6; p = 0.030), and highest hexagonality percentage HEX% (35.1 ± 8.0; p = 0.038). Central corneal thickness was also significantly lower (515.0 ± 26.5 µm; p = 0.027), indicating less postoperative corneal edema. Correspondingly, visual acuity was significantly better (logMAR 0.32 ± 0.19 vs. 0.52–0.54; p = 0.023). Corneal edema had nearly resolved in all groups by one month, and visual acuity differences diminished. Conclusion: OVDs containing SH 2% and mannitol 0.5% offer superior endothelial protection during phacoemulsification in patients with low baseline ECD. In our study, this group showed lower corneal edema rates and faster early visual recovery. This formulation is a suitable option for high-risk cases, such as glaucoma, to enhance surgical safety and visual outcomes.