To preserve or not to preserve, is that the question?

British Journal of Ophthahnology EditorialsTo preserve or not to preserve, is that the question?Over 40 years ago, microbial contamination of eyedrops was reported as a significant risk factor in a series of com- munications describing bacterial keratitis associated with their use.'-5Most of the solutions were of unpreserved fluorescein, but sulphonamides, silver proteinates, alka- loids, methylcellulose, anaesthetics, and sodium chloride were also contaminated.45The predominant contaminant and cause of corneal ulceration was Pseudomonas aeruginosa.5 Also implicated were penicillin eyedrops causing keratitis among industrial workers following removal of