Impact of Lens Case Hygiene Guidelines on Contact Lens Case Contamination

School of Optometry and Vision Science, University of New South Wales, Sydney, New South Wales, Australia.
Optometry and vision science: official publication of the American Academy of Optometry (Impact Factor: 1.6). 07/2011; 88(10):E1180-7. DOI: 10.1097/OPX.0b013e3182282f28
Source: PubMed


Lens case contamination is a risk factor for microbial keratitis. The effectiveness of manufacturers' lens case cleaning guidelines in limiting microbial contamination has not been evaluated in vivo. This study compared the effectiveness of manufacturers' guidelines and an alternative cleaning regimen.
A randomized cross-over clinical trial with two phases (n = 40) was performed. Participants used the lens types of their choice in conjunction with the provided multipurpose solution (containing polyhexamethylene biguanide) for daily wear. In the manufacturers' guideline phase, cases were rinsed with multipurpose solution and air dried. In the alternative regimen phase, cases were rubbed, rinsed with solution, tissue wiped, and air-dried face down. The duration of each phase was 1 month. Lens cases were collected at the end of each phase for microbiological investigation. The levels of microbial contamination were compared, and compliance to both regimens was assessed.
The case contamination rate was 82% (32/39) in the manufacturers' guideline group, compared with 72% (28/39) in the alternative regimen group. There were significantly fewer (p = 0.004) colony forming units (CFU) of bacteria from cases used by following the alternative regimen (CFU range of 0 to 10, and median of 12 CFU per well) compared with that of the manufacturer's guidelines (CFU range of 0 to 10, and median of 28 CFU per well). The compliance level between both guidelines was not significantly different (p > 0.05).
The alternative guidelines are more effective in eliminating microbial contamination from lens cases than that of the current manufacturer's guideline. Simply incorporating rubbing and tissue-wiping steps in daily case hygiene reduces viable organism contamination.

67 Reads
  • [Show abstract] [Hide abstract]
    ABSTRACT: Lens storage case hygiene practices are important for safe contact lens wear. However, the effectiveness of the manufacturer's direction for use and various cleaning regimens in reducing biofilm load is yet to be evaluated and compared. This in vitro study compared the effectiveness of several cleaning methods using silver-impregnated lens case and hydrogen peroxide disinfection systems. Biofilms of Pseudomonas aeruginosa 122 and Staphylococcus aureus ATCC 6538 were grown in silver-impregnated and hydrogen peroxide lens cases. After the establishment of the biofilms, the silver-impregnated case was subjected to one of four cleaning regimens: "manufacturer's directions for use--rinsed and recapped"; "rubbed, rinsed, and recapped"; "rubbed, rinsed, and air dried"; or "rubbed, rinsed, tissue wiped, and air dried." Hydrogen peroxide cases underwent one of two regimens: "manufacturer's directions for use--rinsed with saline and air dried" or "soaked in solution for 6 hrs." The level of residual bacteria was quantified. The efficacy of each cleaning regimen was then compared. Mechanical rubbing and wiping of silver-impregnated cases and soaking hydrogen peroxide cases in hydrogen peroxide were the most effective treatments for reducing biofilms. Once the silver-impregnated cases were rubbed, air drying or recapping the cases did not have any significant effect on the level of the biofilm. The level of initial biofilm formation of silver-impregnated cases was significantly lower than those of polypropylene lens cases (P<0.0001). Rubbing and rinsing with disinfecting solution and wiping with a tissue can be considered to be effective in removing biofilms from silver-impregnated lens cases. Resoaking the basket-type lens case in hydrogen peroxide between use was found to be effective in removing biofilms from these cases.
    Eye & contact lens 11/2011; 37(6):365-9. DOI:10.1097/ICL.0b013e318233c901 · 1.47 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Keratitis is a rare but important and possibly sight threatening complication of Contact Lens wearing. Despite of the number of only about 1.7 keratitis cases per ophthalmolgist per year, this serious side effect needs knowledge and special diagnosis and treatment. Global changes of infectious agents and increase of previously unsuspicious pathogens in combination with a high degress of non-compliance indicate that Contact Lens wearing must be accompanied careful ophthalmologist's medical care and after-care.
    Klinische Monatsblätter für Augenheilkunde 05/2012; 229(5):514-20. DOI:10.1055/s-0031-1299535 · 0.46 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Purpose: To examine the effectiveness of heating contact lens cases after disinfection on reducing microbial contamination. Methods: One strain each of Pseudomonas aeruginosa (071) and Staphylococcus aureus (31) were used to set up robust biofilms in polypropylene contact lens cases. The effect of dilutions (from 1:10 to 1:1000) of trypticase soy broth (TSB) in phosphate-buffered saline and incubation time (24 to 48h) on the ability of strains to from biofilms with high levels of bacteria were first examined. Then the effect of increasing the temperature of incubation (from 14°C to 60°C) of biofilms during drying was examined. In the final set of experiments, biofilms of strains were subjected to heating in a warming device set to deliver 60°C for 3 hours, and the effect of this temperature after disinfection with a multipurpose disinfecting solution (MPDS; containing polyquat and Aldox) was examined by culturing the number of viable bacterial cells remaining. Results: A dilution of 1:100 TSB for S. aureus 31 and 1:1000 TSB for P. aeruginosa 071 together with an incubation time of 24 hours gave high numbers of viable cells of these 2 strains adhered to the contact lens cases. Having established the biofilms of bacteria, heating these to 60°C for 3 hours resulted in significant reductions in the number of viable cells that could be cultured (1 log reduction for S. aureus 31, P=0.0003; 3.5 log reduction for P. aeruginosa 071, P=0.002). Exposing the biofilms of cells to a disinfection cycle (6h at ambient temperature) in the presence of the MPDS and air drying at ambient temperature resulted in 2441±1237 colony-forming units/lens well for S. aureus 31 and 7401±4374 colony-forming units/lens well for P. aeruginosa 071. Increasing the drying temperature to 60°C resulted in zero viable cells (i.e., ≥4log reduction) for either bacterial type. Conclusions: Using a warming device for contact lens cases after a disinfection cycle with an MPDS during drying for 3 hours results in substantial kill of biofilms of P. aeruginosa and S. aureus that have been formed in the wells of the cases.
    Eye & contact lens 08/2012; 38(6). DOI:10.1097/ICL.0b013e318261aa13 · 1.47 Impact Factor
Show more