Journal of Ocular Biology
Research Article
Quantifying Case-Contact Lens Microbial Transmission and the Influence of Care Solutions
Bahr C*, Takeichi R and Yamasaki K
Kobe Laboratory, Ophtecs Corporation, Kobe, Hyogo, Japan
*Address for Correspondence:Charles Bahr, Kobe Laboratory, Ophtecs Corporation, Kobe, Hyogo, Japan.5-2-4 Minatojima-Minami-Machi Kobe, Hyogo, Japan. Email Id:charlie.bahr@gmail.com
Submission: 03 July, 2026
Accepted: 08 August, 2026
Published: 10 August, 2026
Copyright: © 2026 Bahr C, et al. This is an open access article
distributed under the Creative Commons Attribution License, which
permits unrestricted use, distribution, and reproduction in any medium,
provided the original work is properly cited.
Keywords:Contact Lens; Contact Lens Solution; Contact Lens
Case; Microbial Adhesion, Pseudomonas Aeruginosa; Acanthamoeba
Castellanii; Disinfection
Abstract
Purpose: To quantify the case-to-lens transmission of Pseudomonas
aeruginosa and Acanthamoeba castellanii to soft contact lens
materials and to evaluate the disinfecting efficacy of four common
care systems and their impact using a well-plate model.
Methods: Microbe samples were cultured and allowed to adhere to multi-well plates. The disinfection efficacy of four lens care systems — two multipurpose solutions, a hydrogen peroxide system, and a povidone iodine system – was tested and compared to a saline control. Microbial transmission in saline was quantified by placing one of four lens materials (etafilcon A, senofilcon A, Lotrafilcon B, and Balafilcon A) into contaminated wells and exposing them for 4 hours. The lenses were removed, and their acquired microbial load was quantified. The effect of care systems on transmission was evaluated by disinfecting test lenses in contaminated wells with each product, then quantifying their surviving microbial load. Microbial counts were measured with colony-forming units (bacteria) and the Spearman- Karber method (amoebae).
Results: The povidone iodine and hydrogen peroxide systems achieved > 3-log reductions in both pathogens. Both multipurpose solutions failed to meet the 3-log standard against adherent P. aeruginosa and showed negligible activity against A. castellanii. Bacterial transmission to lenses in saline ranged from 1.1% to 3.9%, with Balafilcon A showing the highest uptake. Amoebic transmission varied by material: Lotrafilcon B (11.3%) and Balafilcon A (5.0%) showed higher affinity compared to etafilcon A and senofilcon A (<0.2%). All care systems significantly inhibited transmission relative to saline (by >1 log/mL), although povidone iodine and hydrogen peroxide were the most effective.
Conclusions: Microbial transmission is dependent on the pathogen and the lens material. Povidone iodine and hydrogen peroxide provide superior protection against transmission compared with multipurpose solutions. This transmission model can be used to evaluate the risk of microbial lens colonization in future work.
Methods: Microbe samples were cultured and allowed to adhere to multi-well plates. The disinfection efficacy of four lens care systems — two multipurpose solutions, a hydrogen peroxide system, and a povidone iodine system – was tested and compared to a saline control. Microbial transmission in saline was quantified by placing one of four lens materials (etafilcon A, senofilcon A, Lotrafilcon B, and Balafilcon A) into contaminated wells and exposing them for 4 hours. The lenses were removed, and their acquired microbial load was quantified. The effect of care systems on transmission was evaluated by disinfecting test lenses in contaminated wells with each product, then quantifying their surviving microbial load. Microbial counts were measured with colony-forming units (bacteria) and the Spearman- Karber method (amoebae).
Results: The povidone iodine and hydrogen peroxide systems achieved > 3-log reductions in both pathogens. Both multipurpose solutions failed to meet the 3-log standard against adherent P. aeruginosa and showed negligible activity against A. castellanii. Bacterial transmission to lenses in saline ranged from 1.1% to 3.9%, with Balafilcon A showing the highest uptake. Amoebic transmission varied by material: Lotrafilcon B (11.3%) and Balafilcon A (5.0%) showed higher affinity compared to etafilcon A and senofilcon A (<0.2%). All care systems significantly inhibited transmission relative to saline (by >1 log/mL), although povidone iodine and hydrogen peroxide were the most effective.
Conclusions: Microbial transmission is dependent on the pathogen and the lens material. Povidone iodine and hydrogen peroxide provide superior protection against transmission compared with multipurpose solutions. This transmission model can be used to evaluate the risk of microbial lens colonization in future work.