Disinfection of contact lenses without tap water rinsing: Is it effective?

Abstract

Purpose To establish the efficacy of the two most popular contact lens disinfecting systems -one-step hydrogen peroxide and multi purpose disinfecting solution -for 1 month's use in practice in the absence of tap water rinsing.Methods This was a descriptive, prospective microbiological study of contact lens contamination with ideal hygiene compliance and new lenses and storage cases. One hundred and fifty contact lens wearers were instructed to avoid risk factors identified for Acanthamoeba infection. They were randomly assigned to use one of three disinfecting systems and taught to follow manufacturers'instructions. In addition, they were taught to avoid all use of tap water for contact lens hygiene, except for hand washing. Results There was no isolation ofAcanthamoeba from any lens storage case, precluding the chance of amoebic infection.The multi-purpose solution gave the lowest rate of bacterial contamination, with 78% sterility and 15% of cases with < 10 4 bacteria/ml. For both one-step peroxide and 2. Tap water was NEVER used to rinse or clean the storage case nor to rinse the contact lenses. Only disinfecting fluid was used in the storage case and home-made solutions were disallowed.3. Hands were washed before removing contact lenses, and thoroughly dried on a clean, dry hand towel.4. The contact lenses were cleaned by a 'rub and rinse' technique using the multi-purpose disinfecting solution or hydrogen peroxide as instructed. 5.The contact lenses were placed in the disinfecting solution for overnight storage, and a neutralising tablet was added to the Oxysept hydrogen peroxide system solution.6. In the morning, the contact lenses were removed from the storage case and placed in the eye. The disinfecting solutions used in this study did not require further neutralisation. 7.The solution was tipped out of the storage case, which was left open to air-dry during the daytime when the lenses were worn. The storage case tops of those using the multi-purpose solution were inverted and the case allowed to air-dry.8. Contact lenses were worn on a daily wear basis only and removed for swimming.The contact lens wearer was asked to return the lenses and the storage case, containing the previous night's soaking solution, to the practice after 1 month of use, sealed inside a single-use plastic bag specimen container.It was then stored at 4 °C prior to culture.The participants, all of whom had worn contact lenses for at least 6 months, were randomly assigned to use either a multi-purpose solution (Complete (Allergan), containing 1 ppm or 1 fLg/ml polyhexamethylene biguanide, PHMB) or one of two 'one-step' hydrogen peroxide solutions: Oxysept (Allergan), neutralised by a tablet, or EasySept (Bausch & Lomb), neutralised by a platinum disc within the storage case.Storage cases were observed for dirt and turbid contents. The laboratory investigation included

Incidence and risk factors for microbial keratitis in Hong Kong: comparison with Europe and North America

“…Education of the contact lens-wearing public with informed preventive measures, such as avoidance of overnight (sleeping) wear of hydrogel contact lenses, non-smoking and use of sterile multi-purpose solutions in lens storage cases without tap water, 18 should be cost-effective in reducing the incidence of lensassociated MK in Hong Kong and elsewhere. These measures will be complemented by new ideas such as the incorporation of salicylate into multipurpose solutions, to prevent the formation of biofilm on lenses and the adherence of microbes including Acanthamoeba to them within the storage case.…”

How Could Contact Lens Wearers Be at Risk of Acanthamoeba Infection? A Review

“…Swimming, diving, showering or washing the face while wearing contact lenses was reported to cause Acanthamoeba keratitis. 97,[104][105][106][107][108] The 50-fold increase in the risk of Acanthamoeba keratitis among disposable contact lens users was largely attributable to repeated wear of lenses, lack of disinfection, and use of saline and chlorine-based solutions. 75 The compliance of contact lens users with the recommended care procedures is ineffective if these solutions do not manage to kill Acanthamoeba.…”

“…The use of tap water for the care of contact lenses was widely accepted as the main risk factor in Acanthamoeba infection. 5,85,[97][98][99][100][101][102] In the United Kingdom, 91% of the soft contact lens wearers and 94% of the rigid lens wearers avoided the disease by the complete avoidance of water and the use of powerful lens disinfecting solutions. 5 In the USA, the withdrawal of salt tablets from the market was responsible for the decrease in the incidence of Acanthamoeba keratitis in the mid 80s.…”

Ocular Infections due to Contaminated Solutions

“…The influence of tap water on the presence of Acanthamoeba in CL maintenance was investigated by Seal et al [60]. This study involved the recruiting of 150 CL wearers and careful instruction was given to these patients with respect to possible risk factors for the development of Acanthamoeba infection.…”

“…They were instructed to avoid use of tap water (except for hand washing). They were randomly assigned to one of three disinfecting (two one-step hydrogen peroxide and one multipurpose solution) systems [60]. Results after 1 month’s use consequently demonstrated that Acanthamoeba was not found in any of the 150 cases.…”