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Survey indicates rate of extended wear contact lens fits remains low
Global usage peaked at 12% in 2006, according to a recent study.
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A 5-year international survey of prescribing for extended wear contact lenses concluded that it is unlikely to become a mainstream modality until risks of ocular complications are reduced to those of daily wear contacts.
The survey was conducted in 39 countries from 2006 to 2010 among 107,094 gas-permeable and soft lens fits, of which 88,392 were soft lens daily wear (DW) and 7,470 were soft lens extended wear (EW). The study authors found that EW represented 7.8% of all soft lens fits, failing to break the global “glass ceiling” prescribing rate of 15%, they said.
“If patients are properly educated and warned of the risks of extended wear, then this modality will eventually become safer, increasing practitioner and consumer confidence in extended wear lenses, which will lead to higher prescribing rates of this lens type,” study co-author Nathan Efron, BScOptom, PhD, DSc, FAAO, told Primary Care Optometry News in an interview.
The risk for severe keratitis in EW lens wearers is about 20 cases per 10,000 vs. four cases per 10,000 in DW lenses, according to the study authors.
“When the risks of severe microbial keratitis with overnight lens wear decrease to the same as that for daily lens wear, the rate of extended wear prescribing will increase,” Dr. Efron said.
Nathan Efron
The EW prescribing rate was found to be 7.8% of all soft lens fits, with a considerable variance from 0.6% in Malaysia to 27% in Norway. Differences may exist among nations because of training, extent and nature of commercial and professional promotion of EW, socioeconomic factors and levels of public awareness of eye care, according to the study authors. Provision of contact lenses and associated eye care in large urban centers, as in China, is likely to be different than that of remote, rural areas with limited access to large hospitals and urban infrastructure.
Survey data collected since 1997 was also analyzed to assess EW fitting trends. Between 1997 and 1999, the rate of EW prescribing decreased from 5% to 1% of all soft lens fits, according to the study.
“Up until 1999 we only had hydrogel lenses for extended wear, which were problematic,” Dr. Efron said. “This is why extended wear prescribing fell so low by the end of the 20th century.”
Prescribing rates for EW lenses increased to a peak of 12% in 2006, “resulting from the introduction of highly permeable silicone hydrogel lenses, which significantly improved the overnight ocular response to lens wear because there were fewer hypoxic complications,” he said.
Extended wear prescribing rates settled back to 8% by 2010, “possibly because of the introduction in the mid-2000s of daily wear silicone hydrogel lenses,” Dr. Efron said. “Between 2000 and 2005, silicone hydrogel lenses were only available for extended wear, which drove consumers into that sector.”
Of the EW lenses in the study, 72% were made from silicone hydrogel materials. – by Cheryl DiPietro
Reference:
- Efron N, Morgan PB, Woods, CA, the International Contact Lens Prescribing Survey Consortium. International survey of contact lens prescribing for extended wear. Optom Vis Sci. 2012;89(2):122-129.
For more information:
- Nathan Efron, BScOptom, PhD, DSc, FAAO, can be reached at the School of Optometry and Vision Science, Queensland University of Technology, Kelvin Grove, Queensland 4059, Australia; n.efron@qut.edu.au.
- Disclosure: Dr. Efron has no relevant financial interests to disclose.