Elsevier

Ophthalmology

Volume 119, Issue 8, August 2012, Pages 1516-1521
Ophthalmology

Original article
Risk Factors for Moderate and Severe Microbial Keratitis in Daily Wear Contact Lens Users

https://doi.org/10.1016/j.ophtha.2012.01.052Get rights and content

Objective

To establish risk factors for moderate and severe microbial keratitis among daily contact lens (CL) wearers in Australia.

Design

A prospective, 12-month, population-based, case-control study.

Participants

New cases of moderate and severe microbial keratitis in daily wear CL users presenting in Australia over a 12-month period were identified through surveillance of all ophthalmic practitioners. Case detection was augmented by record audits at major ophthalmic centers. Controls were users of daily wear CLs in the community identified using a national telephone survey.

Testing

Cases and controls were interviewed by telephone to determine subject demographics and CL wear history. Multiple binary logistic regression was used to determine independent risk factors and univariate population attributable risk percentage (PAR%) was estimated for each risk factor.

Main Outcome Measures

Independent risk factors, relative risk (with 95% confidence intervals [CIs]), and PAR%.

Results

There were 90 eligible moderate and severe cases related to daily wear of CLs reported during the study period. We identified 1090 community controls using daily wear CLs. Independent risk factors for moderate and severe keratitis while adjusting for age, gender, and lens material type included poor storage case hygiene 6.4× (95% CI, 1.9–21.8; PAR, 49%), infrequent storage case replacement 5.4× (95% CI, 1.5–18.9; PAR, 27%), solution type 7.2× (95% CI, 2.3–22.5; PAR, 35%), occasional overnight lens use (<1 night per week) 6.5× (95% CI, 1.3–31.7; PAR, 23%), high socioeconomic status 4.1× (95% CI, 1.2–14.4; PAR, 31%), and smoking 3.7× (95% CI, 1.1–12.8; PAR, 31%).

Conclusions

Moderate and severe microbial keratitis associated with daily use of CLs was independently associated with factors likely to cause contamination of CL storage cases (frequency of storage case replacement, hygiene, and solution type). Other factors included occasional overnight use of CLs, smoking, and socioeconomic class. Disease load may be considerably reduced by attention to modifiable risk factors related to CL storage case practice.

Financial Disclosure(s)

Proprietary or commercial disclosure may be found after the references.

Section snippets

Case Ascertainment

New cases of CL-related microbial keratitis were identified in a 12-month, prospective, national surveillance study of all ophthalmic practitioners in Australia, carried out between October 2003 and September 2004. Practitioners were identified through the membership register of the Royal Australian and New Zealand College of Ophthalmologists and were actively surveyed at the end of each 2-month reporting period. Optometrists were identified through the state registration boards and

Results

There were 125 eligible daily wear cases reported during the 12-month study period, including a subgroup of 90 cases of moderate or severe keratitis. Of the 90 cases, 63 were scraped for smear and culture and 41 of 63 (65%) were culture proven. Environmental organisms (Gram-negative bacteria, fungi, and Acanthamoeba) caused severe disease in 32 of 41 (78%) of culture proven cases, with 2 cases (5%) attributed to Acanthamoeba spp. There were no cases of fungal keratitis reported in this cohort.

Discussion

The recent publication of incidence rates for all CL-related microbial keratitis5 has demonstrated that, despite the many advances in CL materials and solutions over the past 15 years, the incidence of infection has remained stable.1, 2, 3 One possible approach to limiting disease morbidity is to identify and address modifiable risk factors associated with moderate or severe microbial keratitis, a subset of microbial keratitis associated with greater morbidity in terms of vision loss, disease

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  • Cited by (0)

    Manuscript no. 2011-1147

    Financial Disclosure(s): The authors have no proprietary or commercial interest in any of the materials discussed in this article.

    This study was supported by the Brien Holden Vision Institute (F.S., T.N.), CIBA Vision (all authors), the University of New South Wales (F.S.), the Vision Cooperative Research Centre (K.E., L.K.), the National Health and Medical Research Council (L.K.). The authors were responsible for design and conduct of the study; collection, management, analysis, and interpretation of the data; and preparation, review, or approval of the manuscript. A draft of the manuscript was provided to the Brien Holden Vision Institute and CIBA Vision before publication, and modifications were limited to clarification and editorial changes.

    The Vision CRC and Brien Holden Vision Institute receive a royalty on the sales of certain contact lenses.

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