Ophthalmic solutions are prepared with the same degree of care as fluids intended for intravenous administration, but once bottles are opened there is always a risk of contamination, particularly with solutions of tetracaine, proparacaine, fluorescein, and any preservative-free preparations The most dangerous is fluorescein, as this solution can be contaminated with P aeruginosa, which can rapidly destroy the eye Single-use fluorescein eye drops or sterile fluorescein filter paper strips are recommended for use in place of multiple-use fluorescein solutions Whether in plastic or glass containers, eye solutions should not remain in use for long periods after the bottle is opened Four weeks after opening is the usual maximum time for use of a solution containing preservatives before discarding Preservative-free preparations should be kept refrigerated and usually discarded within 1 week after opening Single-use products should not be reused If the eye has been injured by accident or by surgical trauma, it is of the greatest importance to use freshly opened bottles of sterile medications or single-use products