Common Ophthalmic Preservatives in Soft Contact Lens Care Products: Benefits, Complications, and a Comparison to Non-Preserved Solutions

Abstract

Purpose: Preservatives are essential for preventing contact lens (CL)-related microbial keratitis (MK). The purpose of this review is to summarize the current knowledge related to the use of common ophthalmic preservatives in CL care products with respect to both safety and efficacy. Methods: Manuscripts written in English were obtained by searching PubMed.gov with the term contact lens plus antimicrobial, benzalkonium chloride, biguanide, Aldox, polyquaternium, preservative, thimerosal, EDTA (ethylenediaminetetraacetic acid), chlorhexidine, or blister pack. Results: This review found that first-generation preservatives are no longer used in CL multipurpose solutions (MPS) due to their high levels of ocular toxicity. Modern, highmolecular-weight preservatives, including polyquaternium-1 (PQ-1) and biguanides (PHMB), are generally effective against bacteria, minimally effective against fungi, and not effective against Acanthamoeba. PQ-1 and PHMB are likely safe when used with CLs, but they may cause ocular adverse events, with roughly equal risk between the two preservatives. Some CL MPS contain both PQ-1 and PHMB, but no increased risk of adverse events has been reported when combining the two. Hydrogen-peroxide (H 2 O 2 ) solutions are effective against all common ocular microbes, including Acanthamoeba, and they have been proven safe with proper compliance. Povidone-iodine (P-I) solutions are not currently commercially available in North America, but they have been shown in other countries to be safe and effective. Conclusion:Patients should be monitored when using PQ-1 or PHMB-containing solutions since they have been associated with ocular adverse events. If events are detected, patients should be switched to an alternative solution. H 2 O 2 or P-I solutions are preferred for any patient who may expose their CLs to water because they are the only solution categories effective against Acanthamoeba.

“Common Ophthalmic Preservatives in Soft Contact Lens Care Products: Benefits, Complications, and a Comparison to Non-Preserved Solutions” [Response to Letter]

“…Erdinest, London, and Levinger for their interest in our article discussing common ophthalmic preservatives in soft contact lens care products. 1 We agree with the authors regarding the physiological effects of polyquaternium-1, polyhexamethylene biguanide (PHMB), and/or borate on the ocular surface. While we did comment on the cytotoxicity of polyquaternium-1 affecting epithelial tight junctions, 2 we did not specify this as oxidative stress or acknowledge the role of tumor necrosis factor alpha (TNF-α) secretion, and we appreciate the added detail.…”

Assessment of genotypes, endosymbionts and clinical characteristics of Acanthamoeba recovered from ocular infection

“…The remaining cases of AK with intracellular bacteria healed when treated only with PHMB and chlorhexidine. This is expected as these antiseptics are also effective against bacteria [ 65 ]. Addition of antibiotics may be advantageous to antiamoebic chemotherapy to abrogate virulence-enhancing traits of intracellular bacteria [ 26 ].…”

Therapy for contact lens-related ulcers

“…In particular, the rise of Fusarium among fungal keratitis has been strongly correlated with contact lens use [19][20][21]. The current generation of multipurpose contact lens solution preservatives do not have full antimicrobial activity and while the most prevalent types, polyquaternium-1 and polyhexamethylene biguanides (PHMB) are effective against most bacteria, they are less effective against fungi, and have no effectivity against Acanthamoeba [22]. Hydrogen-peroxide (H 2 O 2 ) solutions, however, are more effective against all related microbes [22].…”