Comparison of Disinfection Efficacies of Four Contact Lens Care Regimens Against Pseudomonas aeruginosa on Orthokeratology Lenses

Abstract

Purpose: : To compare four types of contact lens care (rigid gas permeable contact lens cleaners, RGPC; hydrogen peroxide solution, H₂O₂; and two povidone iodine solution, for soft lenses & rigid lenses, PVP-IS & PVP-IR) in the disinfection of Pseudomonas aeruginosa from two orthokeratology lenses under experimental conditions.

Methods: : Emerald Lens (oprifocon A, fluorosilicone acrylate-based lens; Euclid Systems Corporation, VA) or Alfa Ortho-K Lens (fluorosilicone methacrylate-based lens; Alpha Corporation, Japan) were incubated in Brain Heart Infusion Broth (BHI; Eiken Chemical Corporation, Japan) containing 10⁵ CFU/ml of Pseudomonas aeruginosa (PAO1) for 15 hours at 36 degrees Celsius to allow attachment to the lens. After incubation, lenses were either rinsed with saline (control) or cleansed by lens care solutions (RGPC: Menicon O2 Care Milfa fresh, Menicon Corporation, Japan; H₂O₂: AOSEPT CLEAR CARE, CIBA VISION Corporation, Japan; PVP-IS: Bioclen First Care CT, Ophtecs Corporation, Japan; PVP-IR: Bioclen O₂ SEPT, Ophtecs Corporation, Japan) according to the manufacturer’s instructions. Also, RGPC was tested in two protocols, with rubbing (following the instructions) and no rubbing. Then, lenses were soaked in BHI, and bacteria were removed by sonication and vortex mixing. The bacterial fluid was spread onto Trypto-soy agar plates (Eiken Chemical Corporation, Japan), incubated for 15 hours at 36 degrees celcius, and colonies were counted. Statistical analysis was performed by Steel-Dwass multiple comparison test.

Results: : The number of Pseudomonas aeruginosa attachment was higher (p<0.01) in fluorosilicone acrylate lenses (1.98 x 10⁸ bacteria/lens) compared to fluorosilicone methacrylate lenses (6.89 x 10⁷ bacteria/lens). All regimens significantly removed bacteria from both lenses compared to control (over 99.99% removal, p<0.01). In fluorosilicone acrylate-based lens, the numbers of remaining bacteria after care were RGPC (no rub) 2658 > RGPC (rub) 666 > PVP-IS 119 = H₂O₂ 47 = PVP-IR 11 (p<0.05). In fluorosilicone methacrylate-based lens, the numbers of remaining bacteria after care were RGPC (no rub) 3316 > PVP-IS 42 = RGPC (rub) 35 = PVP-IR 15 = H₂O₂ 4 (p<0.05).

Conclusions: : Multipurpose solution, hydrogen peroxide solution, and two types of povidone iodine solution showed significant disinfection abilities against Pseudomonas aeruginosa.

Keywords: contact lens • pseudomonas