The debate moves from corneal staining to contact lens–associated infiltrative keratitis. Preservative-associated transient hyperfluorescence is not corneal staining.
Over the past few years, one could not help but notice a shift at ocular society meetings in the discussion regarding multi-purpose solutions (MPS) and contact lenses from asymptomatic “corneal staining” to preservative-associated transient hyperfluorescence (PATH).
In contrast to years past, especially from 2006 to 2009, when “corneal staining” at two hours was a hot topic, there was almost no talk regarding the Andrasko Grid.1 This is due to new compelling research that showed fluorescein is able to enter healthy, dividing cells2 and that the signal seen with MPS (PATH) is reversible and benign3-5 and occurs with all solutions, depending upon when viewed after lens insertion.1,6,7
What is more interesting is that the preservative polyquaternium-1 (Polyquad [PQ-1]), which is found in several MPS that show low levels of PATH at 2 hours, disrupts corneal cell membrane models at 7–8 ppm – levels near or below those found in three marketed solutions.3 This is in contrast to polyhexamethylene (PHMB), a preservative found in several of the solutions showing high levels of PATH at 2 hours, which had no effect on the same corneal cell membrane models at concentrations up to 100 times those found in marketed solutions.4
This article has been reprinted with kind permission from Optician Clinical Editor Bill Harvey and Bioscience Communications and has been significantly edited and updated with current information…
The new science presented at several meetings during 20104,5 and 20113 explains why this phenomenon occurs with certain preservatives at certain time points after lens insertion and has no pathological sequelae. This is further supported by new rigorous studies in the literature that showed PATH is not associated with symptoms, such as reduced comfort,8,9 and that neither corneal staining (as observed during continuous wear) nor PATH is associated with corneal infiltrates,10-12 in contrast to previously published findings that have now been retracted.13,14
Clinically Relevant Findings
A very relevant concern to eye care practitioners (ECPs) are non-infectious corneal inflammatory events, such as contact lens-associated infiltrates/infiltrative keratitis (CLAIK), as an increase in their incidence has been noted by a large proportion of ECPs; especially those in large-volume practices, those that specialise in contact lenses, and those at referral practices.15,16 Reports of an increase in the frequency of infiltrative keratitis (IK)/CLAIK associated with PQ-1/Aldox–based solutions and silicone hydrogel (SiHy) lenses were first observed in 2008 with an increasing number published17-20 and presented at meetings21-24 in the subsequent years with ever increasing frequency.
What is of even greater concern is that one particular PQ-1/Aldox–based solution, which is the soft lens care solution market leader,25 is more closely associated with symptomatic IK (unhappy, red irritated eyes that come into your practice or call you after-hours).17 Moreover, of the symptomatic cases of IK/CLAIK, this PQ-1/Aldox–based solution when used with SiHy, especially senofilcon A, the most popular contact lens, is significantly associated with those of the greatest severity.23
The data regarding which SiHy lens material is associated with infiltrates is not as clear cut. Reports have implicated senofilcon A,18, 19, 21, 23 lotrafilcon A,17 and lotrafilcon B.18 In other reports, no lens association was found with infiltrates, although the leading PQ-1/Aldox–based solution remained an associated factor.22, 24
It’s becoming harder to ignore this signal from so many clinicians and to ignore patient impact.26
Typical case of CLAIK showing central diffuse infiltrates
The Data Keeps Building
Recently published studies confirm that lens and lens case bioburden are associated with an increase in infiltrates.11,27,28
One study evaluated the rate of contamination of cases and the types of microbes contaminating cases. It was found that there were significantly more lens cases, and a higher level of bioburden within these cases due to gram-negative bacteria, with the leading PQ-1/Aldox–based solution (p=0.0001), while cases of those using a PHMB-based MPS and hydrogen peroxide were similar.29 In this same study, the cases of an older PQ-1/Aldox–based solution showed the lowest contamination rate and bacterial bioburden level for any contamination and specifically for gram-negative bacteria (p=0.0001).
These findings show high agreement with the Carnt et al. study published in 200917 as well as the case series by Kislan, where the vast majority of patients were users of the leading PQ-1/Aldox solution and only one patient was using an older PQ-1/Aldox solution.23
The importance of hand washing or the lack thereof with regard to complications, including “sterile” infiltrates30 and microbial keratitis,31 comes up again and again. As clinicians, the majority of us (~92 per cent) recommend rubbing and rinsing contact lenses as part of the cleaning process.32,33 We do this for a reason, and should stop recommending MPS products that do not meet with our professional standard.
Improving Patient Outcomes
Until we have more information there are several practical tactics that can be incorporated into your practice to reduce the likelihood of your patients experiencing an infiltrative event.
Make specific recommendations regarding which solutions to use and why, including:
- A solution that has a new lens case included with the purchase of a new bottle of solution. And encourage them to throw the old one out!
- A solution with a rub and rinse regimen, which aids in decreasing lens bioburden.34
- Recommend to new patients and switch current patients to lens care systems not associated with high rates of IK events and educate patients that there have been a lot of cases of inflammatory problems with these lens care systems.
Give specific instructions on proper lens hygiene, including a demonstration on how to wash one’s hands, lenses, and lens cases between each use.
Keep abreast of contact lens complications by attending scientific meetings and engaging in an ongoing dialogue with colleagues. As practitioners we should be reporting these adverse events to the manufacturer as well as on appropriate local government adverse events tracking sites.
Most important, stay informed by taking the time to review the current literature in addition to research presented at meetings so that you make decisions based on strong scientific evidence.
Marc Bloomenstein, OD. Marc is the director of optometric services at the Schwartz Laser Eye Center in Scottsdale, Arizona. He wishes to thank BioScience Communications for editorial support in the final preparation of this article for publication. This article was originally published in Optician in September 2011. It has been reprinted with kind permission from Optician Clinical Editor Bill Harvey and Bioscience Communications and has been significantly edited and updated with current information.
References
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2. Bakkar M, Maldonado-Codina C, et al. Development of an in-vitro model of solution induced corneal staining. Optom Vis Sci, 2010;87(suppl):E-abstract 100959.
3. Bright FV, Maziarz P, et al. PHMB and PQ-1 impact on a liposome corneal surface membrane model. Invest Ophthalmol Vis Sci, 2011;52:E-Abstract 6491.
4. Bright FV, Maziarz P, et al. Using a liposome cell membrane model to evaluate corneal surface integrity with high dosage polyaminopropyl biguanide (PHMB) exposure. The Annual Global Specialty Lens Symposium; 2010 January 27-30; Las Vegas, NV.
5. Bright FV, Maziarz P, et al. Cell membrane integrity modeling with polyaminopropyl biguanide (PHMB) exposure using fluorescent spectroscopy and liposome assays. The 6th Biennial Scientific Symposium of the Contact Lens Association of Ophthalmologists Education & Research Foundation; 2010 September 23-25; Las Vegas, NV.
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