Reduction of Contamination Rate by Reducing the Volume of Preservative-free 20% Autologous Serum Eye Drops

Abstract

This study investigated whether contamination can be mitigated by halving the filling volume of autologous serum eye drops from 5.0 to 2.5 mL eye drop bottles. Twelve 5.0 mL and eleven 2.5 mL ophthalmic solution bottles were prepared. The ophthalmic solution was all used after opening, leaving one to two drops of the remaining liquid. Immediately after preparation, the remaining liquid was cultured, and, after use, the nozzle and residual liquid were cultured. As a result, twelve 5.0 mL and nine 2.5 mL ophthalmic solution bottles were collected. The average use days of the 5.0 mL ophthalmic solution were 9.6 days and those of the 2.5 mL eye drops were 4.7 days. Bacteria and fungi were not detected from the residual liquid immediately after preparation. However, after use, bacteria were detected in at least one of the nozzles or residual liquid of all eye drops, and fungi were detected in one. Contamination could not be reduced by shortening the period of use of eye drops. Therefore, 20％ autologous serum eye drops need to be handled more appropriately.