Avoiding the use of benzalkonium chloride solutions while contact lenses are in place is discussed in the literature [REF].
Although historically benzalkonium chloride has been ubiquitous as a preservative in ophthalmic preparations, its ocular toxicity and irritant properties,[REF] in conjunction with consumer demand, have led pharmaceutical companies to increase production of preservative-free preparations, or to replace benzalkonium chloride with preservatives which are less harmful.