Article Date: 8/1/2011

Topic: Corneal Infiltrative Events
Point

Topic: Corneal Infiltrative Events

Why Corneal Infiltrates are on the Rise

By Joseph P. Shovlin, OD, FAAO

In recent years, there have been reports of an increase in the rate of non-infectious corneal inflammatory (or infiltrative) events (CIEs) in silicone hydrogel (SiHy) lens wearers (Shovlin and Efron, in press; Morgan et al, 2005), especially in those who use multipurpose solutions (MPSs) (Hine, 2008; Kislan and Hom, 2010; Sacco, 2011). Infiltrative events in users of certain MPSs during daily wear (DW) seem to be increasingly common and are characterized by multiple, diffuse infiltrates that are phenotypically distinct to those described by Sweeney and colleagues (2002).

Risks for and Frequency of CIEs

Factors strongly associated with non-infectious CIEs in contact lens wear are improper contact lens care, contact lens and lens storage case bioburden, extended wear (EW), tight fits or reduced lens movement, and smoking. Several other factors have not been conclusively identified as risks for CIEs, including age (<25 years), MPS use, lens material (SiHy), mucin balls, and time of year, but may play a role (Shovlin and Efron, in press).

Based on the Morgan et al (2005) 12-month epidemiological study, in hydrogel lens wearers, the incidence of non-severe keratitis reported for daily disposable (DD) lenses was 9.1 per 10,000 wearers, and for DW lenses was 14.1 events per 10,000 wearers. The rate for EW is higher, with reported rates of all non-infectious CIEs between 48.2 and 144.6 events per 10,000 wearers (Morgan et al, 2005; Morgan et al, 2005b; Sweeney et al, 2002). In SiHy contact lens users, the incidence of non-severe keratitis was 55.9 events per 10,000 lens wearers during DW and 98.8 events per 10,000 lens wearers when worn on an EW basis (Morgan et al, 2005).

Classification schema may impact incidence and, in part, may be responsible for the inconclusive evidence for several factors in the literature that are observed in clinical settings (Shovlin and Efron, in press; Morgan et al, 2005). Additionally, the rate of non-infectious events is also highly dependent upon the diagnostician. Using the categorical schema developed by Sweeney et al (2002), Efron and Morgan (2006) showed that three events of microbial keratitis (MK) could be diagnosed unambiguously. Seven events could be either MK or contact lens peripherial ulcer (CLPU), and an additional two cases could be either MK, CLPU, or infiltrative keratitis (IK) out of 111 total cases.

Further confounders are that many of these non-infectious events, unlike MK, are self-limiting and may not present to practitioners or be captured in any clinical trial design. Rates of infiltrative events may also be dependant on geographical location.

Ways to Reduce CIEs

Regardless of the inconsistencies among studies, evidence overwhelmingly implicates contact lens care and use, contact lens and lens case microbial contamination, and overnight wear for any apparent increase in events. These factors need to be addressed to improve the outcomes of contact lens wearers. Similarly, certain factors (gender and asymptomatic superficial punctate corneal staining) are not supported as a cause or predisposing factor for non-infectious infiltrative events, and generally need not be factored in clinical decisions for contact lens patients (Shovlin and Efron, in press).

It will be interesting to follow this topic in light of the release of three new MPS formulations. Increasing the use of DD lenses, reducing EW, and better instruction (thereby increasing compliance) may significantly reduce the chances that a patient will develop a non-infectious CIE. CLS

For references, please visit www.clspectrum.com/references.asp and click on document #189.


Dr. Shovlin is a senior optometrist at Northeastern Eye Institute in Scranton, Penn. and serves as adjunct faculty of the Pennsylvania College of Optometry. He is a distinguished practitioner of the National Academy of Practice, diplomate and past chair of the Section on Cornea, Contact Lenses and Refractive Technologies of the American Academy of Optometry, and past chair of the Contact Lens and Cornea Section of the American Optometric Association. He is a consultant or advisor to Alcon, AMO, B+L, Ciba, and Sanofi Pasteur.

Counterpoint

Not Enough Evidence Supports That Infiltrates are on the Rise

By Michael S. Mayers, OD, FAAO

Corneal infiltrative events (CIEs) specifically associated with contact lens wear or multi-purpose solution (MPS) use have recently been a hot topic. Discussions have been conducted through various posters (Kislan, 2011), trade publications (Sacco, 2011), and presentations (Hom and Kislan, AOA 2010), with little supporting evidence in peer-reviewed journals (Kislan and Hom, 2010; Carnt et al, 2009). Some practitioners have reported that specific lens/MPS combinations seem to be more frequently associated with the occurrence of CIEs and are even using the acronym CLAIK (Contact Lens-Associated Infiltrative Keratitis) to describe this specific event.

I do not believe that CIEs are increasing, even though I, like many other practitioners, prescribe a majority of the market share leaders for each category of contact lenses and care solutions. I do see a small percentage of contact lens CIEs in private practice and clinical trials, but these rates and occurrences seem to correspond with what has been reported in the literature.

What's in the Literature

In 2009, Archives of Ophthalmology published a paper called “Contact Lens–Related Adverse Events and the Silicone Hydrogel Lenses and Daily Wear Care System Used” (Carnt et al, 2009). This was one of the first published studies to examine the frequency of CIEs with specific lens/care solution combinations in daily wear with a focus on silicone hydrogel materials. The results during a three-month follow-up period revealed a total CIE (asymptomatic and symptomatic) frequency rate of 3.1 percent, most of which were described as infiltrative keratitis. The frequency rate for symptomatic CIEs was 1.7 percent. The research showed no relation between CIEs and lens type or lens/care solution combination. There was a difference in CIE rates based on care solution, with the rate of CIEs being lowest when patients were using the hydrogen peroxide-based care system. However, the open-label/nonmasked (both subjects and investigators), and nonrandomized nature of the study, in addition to the unequal number of subjects allowed to repeat the study in a different lens/care solution combination, may challenge some of its validity. That being said, the incidence rates found for CIEs were similar to earlier published data on the rates of occurrence of CIEs in daily wear hydrogel lens wearers (Stapleton et al, 2007).

At the most recent Association for Research in Vision and Ophthalmology (ARVO) meeting, Chalmers et al (2011) presented a poster called “Risk Factors for Corneal Infiltrative Events in Soft Contact Lens (SCL) Wearers: A Case Control Study in 2010.” This retrospective study was a chart review at five academic sites that went back to 2006. The investigators identified 166 patients who had been diagnosed with CIEs. The cases identified were then graded by a masked panel of expert clinicians, and other factors related to the occurrences were recorded. The results showed no association between a specific lens/care solution combination and the occurrence of a CIE. Leading factors associated with CIEs were younger patients, extended wear, silicone hydrogels, and reusable lenses.

No Conclusive Evidence

From my clinical experience and review of existing published data, I believe that CIEs are not necessarily on the rise, and that a specific lens, MPS, or combination of the two have not clearly been identified by proper research. Any such claims should be avoided until substantive, properly controlled research confirms such a connection. CLS

For references, please visit www.clspectrum.com/references.asp and click on document #189.


Dr. Mayers has served as a National Board Examiner and has lectured nationally on various topics. He is a fellow of the American Academy of Optometry and conducts clinical trials on contact lenses, lens care solutions, and dry eye. He has received honoraria or research funding from Alcon, B+L, Ciba, Merck (previously Inspire), Johnson & Johnson, and Visioneering Technologies. He practices in Powell, Ohio, where he founded Mayers Eye Solutions LLC. E-mail him at mayersod@gmail.com.

Contact Lens Spectrum, Issue: August 2011