Long-term Stability of Epitheliotropic Factors in Frozen Serum Eye Drops

The objective of this experimental study was to investigate the stability of functional proteins in human serum eye drops, which are used for the treatment of ocular surface disorders, after prolonged storage of 6 months at -20°C. After obtaining whole blood from 3 volunteers and preparing 100% (S100), 50% (S50), and 20% (S20) serum eye drops, fibronectin was quantified before and after storage for 6 months at -20°C using appropriate enzyme-linked immunoassay kits. The pH and microbial contamination of preparations were also evaluated longitudinally. The fibronectin concentration showed no significant reduction in undiluted (S100) or diluted (S50 and S20) serum after 6 months of frozen storage at -20°C. None of the preparations showed any microbial contamination and no significant changes in pH were noted during storage. Frozen serum eye drops appear stable after prolonged storage at -20°C. Fibronectin in serum is temperature and time resistant after prolonged storage at -20°C. While the impact of individual serum proteins on ocular surface health remains unclear, our results suggest that freezing up to 6 months provides adequate preservation of epitheliotropic factors and a minimal risk of microbial contamination.