Contact Lens Spectrum Supplements

Special Edition 2017

Contact Lens Spectrum

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C O N T A C T L E N S S P E C T R U M S P E C I A L E D I T I O N 2 0 1 7 c l s p e c t r u m . c o m 6 RESEARCH REVIEW S. B A R RY E I D E N, O D with contact lens wear was pub- lished in 1989 by Schein et al. The authors stated that ulcerative kerati- tis was the most serious adverse ef- fect of contact lens use. They conducted a case-control study estimating the relative risk of ulcerative keratitis among users of extended wear as compared with daily wear soft contact lenses. This relative risk among the population- based controls was 3.90 (95% con- fidence interval [CI], 2.35 to 6.48), and among the hospital-based con- trols it was 4.21 (95% CI, 1.95 to 9.08). Thirty-eight percent of the patients who wore extended-wear lenses used them only during the day, and 11% of those who wore daily wear lenses occasionally wore them overnight. When lens wearers were distin- guished according to their overnight use of lenses, the users of extended wear lenses who wore them over- night had a risk 10 to 15 times as great as the users of daily wear lens- es who did not, and the users of dai- ly wear lenses who sometimes wore them overnight had nine times the risk of the users of such lenses who did not. For the users of extended daily wear GP lenses, 3.5 per 10,000 (2.7 to 4.5) users of daily wear soft lenses, and 20.0 per 10,000 (10.3 to 35.0) users of extended wear soft lenses (p < 0.00001 for comparison between all groups). A study from Australia (Stapleton et al, 2008) found that the annual- ized incidence of MK per 10,000 wearers was 1.2 (CI, 1.1 to 1.5) in daily wear GP wearers; 1.9 (CI, 1.8 to 2.0) in daily wear soft contact lens wearers; 2.2 (CI, 2.0 to 2.5) in soft contact lens wearers (occa- sional overnight use); 2.0 (CI, 1.7 to 2.4) in daily disposable contact lens wearers; 4.2 (CI, 3.1 to 6.6) in daily disposable contact lens wear- ers (occasional overnight use); 11.9 (CI, 10.0 to 14.6) in daily wear sili- cone hydrogel lens wearers; 5.5 (CI, 4.5 to 7.2) in silicone hydrogel lens wearers (occasional overnight use); 19.5 (CI, 14.6 to 29.5) in overnight wear soft contact lens wearers; and 25.4 (CI, 21.2 in 31.5) in overnight wear of silicone hydrogel contact lenses. Loss of vision occurred in 0.6 per 10,000 wearers. Risk factors included overnight lens wear, poor storage case hy- giene, smoking, internet purchase of contact lenses, < 6 months of wearing experience, and higher so- cioeconomic class. Although there have been significant developments in contact lens material science since the first MK incidence studies were published, it appears that the dramatic increase in oxygen per- meability of contact lenses has had little effect on the incidence rates of MK. The authors of this study stated that incidence estimates for soft contact lens use were similar to wear lenses, the risk of ulcerative keratitis was incrementally related to the extent of overnight wear. The authors concluded that soft contact lenses worn overnight carry a sig- nificantly greater risk for ulcerative keratitis compared with soft lenses worn only during the day. Liesegang (1997) reviewed avail- able epidemiologic data pertaining to contact lens-related MK. The incidence rates for bacterial MK range from approximately 2/10,000 per year for rigid contact lenses to 2.2 to 4.1/10,000 per year for daily wear soft contact lens to 13.3 to 20.9/10,000 per year for extended wear soft contact lenses. The risk with therapeutic contact lenses, however, was much higher: approx- imately 52/10,000 per year. The au- thors stated that the most significant risk factors include overnight wear, smoking, male gender, and socio- economic status. Confirming studies subsequently have been published that showed similar rates of MK. A study from the Netherlands (Cheng et al, 1999) found an estimated annual- ized incidence of MK of 1.1 per 10,000 (95% CI, 0.6 to 1.7) users of MICROBIAL KERATITIS AND SPECIALTY CONTACT LENS WEAR C ontact lenses are a safe and effective vision correction option and have positively impacted our patients' lives for many years. However, there exists an ever pres- ent risk of corneal infection or microbial keratitis (MK), which occurs at higher rates in contact lens wearers compared with non-lens wearers who have no other risk factors. We will explore in this article what current re- search tells us about the risk of MK with contact lens wear in general and then relate this specifically to specialty contact lens wear. Comparing Modalities of Contact Lens Wear and Risk of MK The study that first opened our eyes to the relative risk of MK associated

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