Extended wear and continuous wear are synonymous terms that describe a modality of overnight contact lens wear, usually for a period of one to four weeks. Soft hydrogel lenses, including the latest highly gas-permeable silicone hydrogel lenses, and rigid gas permeable lenses have been used for extended wear. Extended wear lenses have proven popular because of their convenience. However, concerns regarding the relative safety of soft hydrogel lenses for extended wear prompted several studies to examine the rate of adverse reactions among users of such contract lenses.
In a series of studies1-7 the risk of developing ulcerative keratitis with soft hydrogel lenses was:
a) Ten to 15 times greater in extended wear versus daily wear users;
b) Nine times greater in elderly patients using extended wear lenses for correction of aphakia;
c) Twelve times greater in individuals misusing daily wear lenses for overnight wear;
d) Proportionally greater with increased consecutive days of extended wear lens wear before removal;
e) Less with more frequent lens removal, lens care, and especially with frequent contact lens case cleaning.
Overnight wear, regardless of contact lens type, increases the likelihood of corneal infection.3,5,6,8-11 A small percentage of patients that were fitted with gas-permeable soft silicone hydrogel contact lenses developed sterile inflammatory peripheral corneal infiltrates within one year of use.12 A study of patients using silicone hydrogel contact lenses continuously for up to 30 days concluded that the overall rate of microbial keratitis was similar to that of conventional soft extended wear lenses.8 These lenses are FDA approved for 30 days of extended wear.
The FDA recommends that overnight wear soft hydrogel lenses be removed and not worn overnight at least once a week for overnight cleaning and disinfection. Disposable lenses for extended wear should also be discarded on a regular basis consistent with manufacturers' recommendations or the specific instructions of their eye care professional.
Disposable (or programmed replacement) contact lenses do not reduce the risk of ulcerative keratitis with extended wear. Overnight wear of contact lenses is the main risk factor for all types of ulcerative keratitis, whether or not the lenses are disposable.3-6 The requirements for user compliance with contact lens and lens case cleaning and disinfection regimes, scheduled lens and lens case replacement, and follow-up must be emphasized when discussing the risks of overnight wear with patients.
Acanthamoeba keratitis is an infrequent but serious microbial infection among contact lens wearers. Several FDA-mandated clinical studies carried out into the late 1990s have confirmed that overnight wear of contact lenses is the most important risk factor for microbial keratitis. The incidence of microbial keratitis is similar whether disposable or conventional soft contact lenses are used for overnight wear. However, disposable lenses are more often associated with relatively benign peripheral infiltrates than with the aggressive central microbial keratitis, which is common with conventional soft lenses used for overnight wear.6,7,13 Also, due to the increased risk of Acanthamoeba keratitis among individuals using homemade saline solutions for lens care, the FDA has banned the sale of salt tablets for such solutions. Red eye and discomfort may signal early infection with Acanthamoeba keratitis or another microorganism. Any individual using extended wear contact lenses that develops symptoms should remove the lens and see an ophthalmologist promptly.
Note: Environmental risk factors and hygiene practices, such as no-rub cleaning, topping off to reuse solutions, contaminated lens cases, exposure to tap water, wearing contact lenses in hot tubs, and changes in water supply are emerging as possible risk factors for the increases in Acanthamoeba and fungal keratitis in association with contact lens use in the past decade.14-35
Patients should be instructed that rubbing is an important part of the cleaning step before disinfection for any lens that will be re-worn. Rubbing the contact lens enhances the cleaning performance of the solution, likely by removing loosely bound deposits. Lens intolerance associated with these deposits, including giant papillary conjunctivitis, is higher in extended wear soft lens users. These conditions may necessitate changing the lens or discontinuing the use of soft contact lenses. Hydrogen peroxide systems may be superior to preserved disinfecting solutions in reducing pathogen binding and cysticidal disinfection, but they require more complex care regimens.36-39 Patients should be instructed to use only sterile products that are commercially prepared specifically for contact lens care and to replace these at the intervals recommended by the manufacturers.40 Specifically, patients should be instructed not to rinse contact lenses or lens cases with nonsterile water (e.g., tap water or bottled water).41 Patients should also be instructed to clean and replace contact lens cases frequently, because they can be a source of lens contamination.29,40,41 Patients should be instructed to replace the solution in contact lens cases each time the lenses are disinfected (i.e., the old solution should not be topped off).42
The American Academy of Ophthalmology recognizes that the extended wear of contact lenses can be a useful and safe method of correcting refractive errors in properly selected and carefully monitored users. However, the extended wear of contact lenses has the potential for causing severe ocular damage when there is inadequate instruction, lack of user compliance, and insufficient professional supervision. Although there are lenses approved by the FDA for extended wear, the risks, benefits, and alternatives should be presented to patients considering this mode of contact lens wear. The incidence of complications, particularly infectious keratitis, is higher with extended wear soft hydrogel lenses. Studies confirm the importance of good education, hygiene, and compliance for safe and successful extended contact lens wear. Practitioners, such as ophthalmologists, who have the professional training and experience to recognize and treat potential complications should fit extended wear contact lenses and monitor patients.
MacRae S, Herman C, Stulting RD, et al. Corneal ulcer and adverse reaction rates in premarket contact lens studies. Am J Ophthalmol 1991;111:457-465.
- Schein OD, Glynn RJ, Poggio EC, et al. The relative risk of ulcerative keratitis between extended- and daily-wear soft contact lens wearers: A case-control study. N Engl J Med 1989;321:773-778.
- Poggio EC, Glynn RJ, Schein OD, et al. The incidence of ulcerative keratitis among daily and extended-wear soft contact lens wearers. N Engl J Med 1989;321:779-83.
- Matthews TD, Frazer DG, Minassian DC, et al. Risk of keratitis and patterns of use with disposable contact lenses. Arch Ophthalmol 1992;110:1559-1562.
- Schein OD, Buehler PO, Stamler JF, et al. The impact of overnight wear on the risk of contact lens-associated ulcerative keratitis. Arch Ophthalmol 1994;112:186-190.
- Nilsson SE, Montan PG. The annualized incidence of contact lens induced keratitis in Sweden and its relation to lens type and wear schedule: results of a 3-month prospective study. CLAO J 1994;20:225-30.
- Nilsson SE, Montan PG. The hospitalized cases of contact lens induced keratitis in Sweden and their relationship to lens type and wear schedule: results of a three-year retrospective study. CLAO J 1994;20:97-101.
- Schein OD, McNally JJ, Katz J, et al. The incidence of microbial keratitis among wearers of a 30-day silicone hydrogel extended-wear contact lens. Ophthalmology 2005;112:2172-9.
- Dart JK, Radford CF, Minassian D, et al. Risk factors for microbial keratitis with contemporary contact lenses: a case-control study. Ophthalmology 2008;115:1647-54, 54 e1-3.
- Stapleton F, Keay L, Edwards K, et al. The incidence of contact lens-related microbial keratitis in Australia. Ophthalmology 2008;115:1655-62.
- Mondino BJ, Weissman BA, Farb MD, Pettit TH. Corneal ulcers associated with daily-wear and extended-wear contact lenses. Am J Ophthalmol 1986;102:58-65.
- Nilsson SE. Seven-day extended wear and 30-day continuous wear of high oxygen transmissibility soft silicone hydrogel contact lenses: a randomized 1-year study of 504 patients. CLAO J 2001;27:125-136.
- Poggio EC, Abelson M. Complications and symptoms in disposable extended wear lenses compared with conventional soft daily wear and soft extended wear lenses. CLAO J 1993;19:31-9.
- American Society of Cataract and Refractive Surgery Infectious Disease Task Force. ASCRS White Paper. Special Report: Acanthamoeba Keratitis. July 2007. Available at: http://www.ascrs.org/clinical-reports/acanthamoeba-keratitis-guidelines-2007. Accessed April 2, 2013.
- Butcko V, McMahon TT, Joslin CE, Jones L. Microbial keratitis and the role of rub and rinsing. Eye Contact Lens 2007;33:421-3; discussion 424-5.
- Khor WB, Aung T, Saw SM, et al. An outbreak of Fusarium keratitis associated with contact lens wear in Singapore. JAMA 2006;295:2867-73.
- Acanthamoeba keratitis multiple states, 2005-2007. MMWR Morb Mortal Wkly Rep 2007;56:532-4.
- Alfonso EC, Cantu-Dibildox J, Munir WM, et al. Insurgence of Fusarium keratitis associated with contact lens wear. Arch Ophthalmol 2006;124:941-7.
- Bernal MD, Acharya NR, Lietman TM, et al. Outbreak of Fusarium keratitis in soft contact lens wearers in San Francisco. Arch Ophthalmol 2006;124:1051-3.
- Chang DC, Grant GB, O'Donnell K, et al. Multistate outbreak of Fusarium keratitis associated with use of a contact lens solution. JAMA 2006;296:953-63.
- Joslin CE, Tu EY, McMahon TT, et al. Epidemiological characteristics of a Chicago-area Acanthamoeba keratitis outbreak. Am J Ophthalmol 2006;142:212-7.
- Joslin CE, Tu EY, Shoff ME, et al. The association of contact lens solution use and acanthamoeba keratitis. Am J Ophthalmol 2007;144:169-80.
- Thebpatiphat N, Hammersmith KM, Rocha FN, et al. Acanthamoeba keratitis: a parasite on the rise. Cornea 2007;26:701-6.
- Saw SM, Ooi PL, Tan DT, et al. Risk factors for contact lens-related fusarium keratitis: a case-control study in Singapore. Arch Ophthalmol 2007;125:611-7.
- Update: Fusarium keratitis--United States, 2005-2006. MMWR Morb Mortal Wkly Rep 2006;55:563-4.
- Alfonso EC, Miller D, Cantu-Dibildox J, et al. Fungal keratitis associated with non-therapeutic soft contact lenses. Am J Ophthalmol 2006;142:154-5.
- Anger C, Lally JM. Acanthamoeba: a review of its potential to cause keratitis, current lens care solution disinfection standards and methodologies, and strategies to reduce patient risk. Eye Contact Lens 2008;34:247-53.
- Dyavaiah M, Ramani R, Chu DS, et al. Molecular characterization, biofilm analysis and experimental biofouling study of Fusarium isolates from recent cases of fungal keratitis in New York State. BMC Ophthalmol 2007;7:1.
- Hall BJ, Jones L. Contact lens cases: the missing link in contact lens safety? Eye Contact Lens 2010;36:101-5.
- Levy B, Heiler D, Norton S. Report on testing from an investigation of fusarium keratitis in contact lens wearers. Eye Contact Lens 2006;32:256-61.
- Lindsay RG, Watters G, Johnson R, et al. Acanthamoeba keratitis and contact lens wear. Clin Exp Optom 2007;90:351-60.
- Gower EW, Keay LJ, Oechsler RA, et al. Trends in fungal keratitis in the United States, 2001 to 2007. Ophthalmology 2010;117:2263-7.
- Iyer SA, Tuli SS, Wagoner RC. Fungal keratitis: emerging trends and treatment outcomes. Eye Contact Lens 2006;32:267-71.
- Tu EY, Joslin CE. Recent outbreaks of atypical contact lens-related keratitis: what have we learned? Am J Ophthalmol 2010;150:602-8.
- Tuli SS, Iyer SA, Driebe WT, Jr. Fungal keratitis and contact lenses: an old enemy unrecognized or a new nemesis on the block? Eye Contact Lens 2007;33:415-7; discussion 424-5.
- Cavanagh HD, Robertson DM, Petroll WM, Jester JV. Castroviejo Lecture 2009: 40 years in search of the perfect contact lens. Cornea 2010;29:1075-85.
- Johnston SP, Sriram R, Qvarnstrom Y, et al. Resistance of Acanthamoeba cysts to disinfection in multiple contact lens solutions. J Clin Microbiol 2009;47:2040-5.
- Hughes R, Kilvington S. Comparison of hydrogen peroxide contact lens disinfection systems and solutions against Acanthamoeba polyphaga. Antimicrob Agents Chemother 2001;45:2038-43.
- Wu YT, Zhu H, Willcox M, Stapleton F. The effectiveness of various cleaning regimens and current guidelines in contact lens case biofilm removal. Invest Ophthalmol Vis Sci 2011;52:5287-92.
- Acanthamoeba keratitis associated with contact lenses--United States. MMWR Morb Mortal Wkly Rep 1986;35:405-8.
- Stapleton F, Edwards K, Keay L, et al. Risk factors for moderate and severe microbial keratitis in daily wear contact lens users. Ophthalmology 2012;119:1516-21.
- U.S. Food and Drug Administration. Guidance for Industry, FDA Staff, Eye Care Professionals, and Consumers. Decorative, non-corrective contact lenses. November 24, 2006. Available at: http://www.fda.gov/MedicalDevices/DeviceRegulationandGuidance/GuidanceDocuments/ucm071572.htm. Accessed February 3, 2013.
Issued August 2004; revised January 2008; re-revised May 2013
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