13 For more information on diagnosis and treatment of Fusarium and Acanthamoeba, see Chapter 21.Ĭhemical disinfection may be used on all types of lenses and has little effect on lens life. 12 Other wearer tips to minimize the risk for Acanthamoeba keratitis include if lenses are worn during swimming, airtight goggles should be worn and, if not, the lenses should be disposed immediately after swimming. 11 The effects of chemical disinfection alone on Acanthamoeba and the human immunodeficiency virus (HIV) are minimal. 10 As would be expected, one study found that the care regimen (chemical or oxidative) is most effective when all steps are performed (i.e., rubbing, rinsing, and disinfecting). 9 Digital rubbing and rinsing have been found to remove up to 99% of Acanthamoeba found on a lens before chemical disinfection. 7, 8 Digital rubbing in these chemical regimens is important in removing Acanthamoeba from the lens. Recent outbreaks of Acanthamoeba keratitis may be associated with changes in water purification. 5, 6 The risk of Acanthamoeba keratitis is increased by tap water use, swimming, use of hot tubs and showering with contact lenses on, and improper care. 4 Extended wear, noncompliance, and poor lens hygiene increase the chances of a fungal infection. Although patient noncompliance may be partially responsible in these two outbreaks, it is also believed that the disinfection efficacy of these two solutions was decreased, part of the formulation facilitated the pathogen growth, and the solution caused disruption to the corneal surface creating a portal for the infection to occur. Chemical care regimens have been removed from the market because of cases of Fusarium (ReNu MoistureLoc) and Acanthamoeba (Complete Moisture Plus) that were linked to the use of these solutions. If in doubt, changing the patient to a nonpreserved care regimen or a daily disposable contact lens modality may eliminate the symptoms.Īdditionally, the preservatives in chemical care regimens are not as effective against bacteria, fungi, and Acanthamoeba as hydrogen peroxide care regimens. 3 Although the sensitivity rate may be lower with the newer preservatives, the practitioner needs to be aware that symptoms of sensitivity to them may be delayed and somewhat vague. The three chemical care regimens resulted in inducing more corneal staining to a small extent in the Staining Grid study and even more in the IER Matrix study. Both studies found a hydrogen peroxide care regimen (ClearCare, Ciba Vision) to perform well with four silicone hydrogel materials (Acuvue Advance & Acuvue Oasys, Vistakon O 2Optix, Ciba Vision and PureVision, Bausch & Lomb). The IER study investigators looked for the presence of staining three times over a 3-month period. In the Staining Grid study, staining was assessed after 2 hours of wear and overnight soaking. 2 The Andrasko Staining Grid and the Institute for Eye Research (IER) Matrix both pertained to solution-induced corneal staining. A study with adolescents found that overall, patients on a hydrogen peroxide system show less staining and inflammatory response than those patients using a chemical care regimen. Changing the patient to a preservative-free, hydrogen peroxide care regimen alleviates the dry-eye symptoms. 1 The soft contact lens wearer using a multipurpose chemical solution presents with normal external findings, but complains of ocular dryness. A condition called multipurpose nonkeratitis has been reported. Occasionally, some patients may stillĮxhibit sensitivity, reporting symptoms of dryness, itching, burning, injection, decreased wearing time, and discomfort. The preservatives currently used cause less patient sensitivity. Although both of these preservatives exhibit excellent preservative action, many patients were sensitive to them. The problem that originally became apparent with chemical disinfection systems was the use of preservatives, such as thimerosal and chlorhexidine.
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