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Microbial keratitis: Prevention through proper contact lens hygiene.
December 28, 2011
Ankit Shah BS1, Harpreet S. Walia MD2, Son Ho MD3
University of South Florida College of Medicine, Tampa, FL
Emory Eye Center, Atlanta, GA
Tulane University Department of Ophthalmology, New Orleans, LA
The cornea is the clear front film of the eye responsible for focusing light so that images we see can project onto the retina, similar in function to the lens of a camera. Therefore, any injury to the surface of the cornea will block light from entering into the eye and cause permanent vision loss. One of the leading causes of corneal injury is a direct result of infections from bacteria, viruses, and fungi. The eye is capable of protecting the cornea from damage by constantly producing tears which help wash away the bacteria. . The tear film of the eye contains a layer of enzymes and proteins which bind, destroy, and prevent bacteria from entering the cornea. However, when the eye becomes irritated it may cause microscopic cuts in the cornea and provide an entry way for bacteria to infect the eye
It is estimated that every year approximately 25,000 incidents of bacterial keratitis are reported in the United States, a number even greater when viral and fungal causes are included. A large fraction of these cases originate from improper contact lens use and hygiene. Symptoms of microbial keratitis include redness, pain, blurry vision, and discharge from the eye. If untreated, it may result in permanent blindness. Patients who regularly wear contact lens suffer more commonly from irritated eyes and thus are more susceptible to corneal infection. This is either due to the contact lens drying the eyes, causing friction with the cornea, or from an adverse reaction to the contact lens solution.
The most effective way to reduce the incidence of contact lens induced keratitis is by preventing such infections from occurring in the first place. For instance, proper eye hygiene and contact lens care can drastically reduce the chance of infection. The following paragraphs discusses proper contact lens hygiene and provide general guidelines for contact lens wearers.
The most important precaution that contact lens wearers must take is to follow proper lens instructions given by their ophthalmologist or technician. This includes wearing and replacing contact lens strictly according to their schedules because prolonged use may cause further contamination. Furthermore, contact lens cases should be replaced every three months, and cleaned weekly by soaking in boiling water for ten minutes. Both the lens and the case are to be rinsed daily using appropriate cleaning solution. Water and home based cleaning solutions are not considered appropriate disinfectant solutions and should not be used to clean contact lens. It is important that patients understand to replace the contact solution in the cases each time the lens is cleaned. These measures help prevent bacterial from growing in the cases and the lens.
Patient who begin to wear contact lens for the first time should be comfortable with inserting and removing them prior to leaving clinic. An important facet of contact lens hygiene involves washing hands thoroughly with soap and water prior to any contact with the lens. It is extremely important for lens wearers to avoid wearing contact lens overnight or while swimming because this makes contact lens removal difficult. Patients should also be proactive in discussing with the physician signs and symptoms to recognize early when suspecting a developing corneal infection. In cases where the eye does become red, or if pain and discomfort is felt in, the patient should remove the contact lens immediately and contact an ophthalmologist.
The intent of this article is to educate patients about general accepted guidelines for proper contact lens hygiene in hopes to reduce the incidence of microbial keratitis.
1. Preferred Practice Patterns, Bacterial Keratitis. American Academy of Ophthalmology
2. Hickson-Curran S, Chalmers RL, Riley C. Patient attitudes and behavior regarding hygiene and replacement of soft contact lenses and storage cases. Cont Lens Anterior Eye. 2011 Octl34(5):2015
3. Robertson DM, Cavanagh HD. Non-compliance with contact lens wear and care practices: acomparative analysis. Optom Vis Sci. 2011 Dec; 88(12): 1402-8
4. Wu YT, Tend YJ, Nicholas M, et al. Impact of lens case hygiene guidelines on contact lens case contamination. Optom Vis Sci. 2011 Oct;88(10):E1180-7.