Editorial: Contact lens-associated keratitis

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1*Pennsylvania College of Optometry at Salus University, Eye- and Vision Center Optometrie Cagnolati GmbH

Microbial keratitis is an infection of the eyes that threatens vision. It can be caused by bacteria, fungi or protozoa. Insufficient contact lens hygiene is one of the causes of microbial keratitis.1

Fleiszig et al. reported an estimated annual incidence of contact lens-associated microbial keratitis oft 2 to 20 cases per 10,000 contact lens wearers.2 Soft contact lens wearers are more likely to be affected than users of rigid contact lenses.3

Based on a very comprehensive literature review, Maier et al. from the Department of Ophthalmology, University Hospital Freiburg, Germany, recently discussed, among others, the risk factors for the development of contact lens-associated keratitis.4 The data of the Freiburg publication also confirm that soft contact lens wearers are affected in the majority of cases. Sixty-nine percent of those affected with microbial keratitis at the Freiburg University Eye Clinic in 2021 were wearers of soft contact lenses and three percent wearers of RGP contact lenses. According to the literature study by Mayer et al., the risk factors for contact lens-associated keratitis include a 3.6- to 11-fold increased risk of poor hygiene, water contact, and no hand washing. The authors also mention a 4.8-fold increase in risk factors for contact lens-associated keratitis in the context of ordering contact lenses online by Internet.

Optometrists, opticians and ophthalmologists are well aware of the often inadequate contact lens hygiene of many contact lens wearers. This makes it even more important to carefully instruct patients when first providing the lenses. At regular contact lens check-ups, in addition to the examination of the anterior segment of the eye, the surface quality and possible distortation of the lenses should also be checked. As patients are often instructed in the handling and use of contact lenses as well as lens hygiene by the assistants, these also need to be trained regularly and their knowledge constantly updated. Safe and complication-free contact lens wear requires not only an individual fitting of the lenses, but also regular follow-up checks and contact lens hygiene suitable for the contact lens wearer and the fitted lenses.

Only one percent of contact lens wearers are following the necessary contact lens hygiene as well as the recommended wearing modalities.Changing this behavior is a major challenge for the eye care professions.


[1] Cope, J. R., Collier, S. A., Rao, M. M., Chalmers, R., Mitchell, G. L., Richdale, K., Wagner, H., Kinoshita, B. T., Lam, D. Y., Sorbara, L., Zimmermann, A., Yoder, J. S., Beach, M. J. (2015). Contact lens wearer demographics and risk behaviors for contact lens-related eye infections – United States. MMWR Morb. Mortal. Wkly. Rep., 64, 865–870.

[2] Fleiszig, S. M. J., Kroken, A. R., Nieto, V., Grosser, M. R., Wan, S. J., Metruccio, M. M. E., Evans, D. J. (2020). Contact lens-related corneal infection: Intrinsic resistance and its compromise. Prog. Retin. Eye Res., 76,100804.

[3] Seal, D. V., Kirkness, C. M., Bennett, H. G., Peterson, M., (1999). Keratitis Study Group: Population-based cohort study of microbial keratitis in Scotland: incidence and features. Cont. Lens Anterior Eye, 22, 49–57.

[4] Maier, P., Kamrath Betancor, P., Rein­hard, T. (2022). Contact Lens–Associated Keratitis – an Often Underestimated Risk. Dtsch. Arztebl. Int., 119, 669–674.