IER Matrix Study establishes ‘real world’ silicone hydrogel solution guide

Sydney, Australia, 6 September 2007: Silicone hydrogel lens wearers came closer to ‘the perfect choice’ this week when research conducted at the Institute for Eye Research (IER) revealed the latest data on combinations of contact lens solutions and a range of silicone hydrogels.

The Institute for Eye Research Matrix Study, published in the September 2007 edition of Contact Lens Spectrum, puts under the microscope four leading brands of lenses; ACUVUE® ADVANCETM and ACUVUE® OASYSTM (Johnson and Johnson Vision Care Inc, Jacksonville, USA), O2OPTIXTM (CIBA Vision, Atlanta, USA) and PureVision® (Bausch and Lomb, Rochester, USA) used in combination with four brands of disinfecting solutions: AOSeptPlus® (Clear Care) (CIBA Vision), AQuify® (SOLOCARE AQUA™) MPS (CIBA Vision), OPTI-FREE® Express® and OPTI-FREE® RepleniSH® (Alcon Laboratories Inc, Fort Worth, USA).

The IER Matrix study results released thus far report on 640 experienced and new contact lens wearers in 16 groups of 40, who used each type of silicone hydrogel lenses bilaterally in conjunction with each type of multipurpose solutions on daily wear and were monitored over three months.

“Solution induced corneal staining (SICS) varies with the choice of lens care solutions and does not obey the same rules as with conventional hydrogels,” said researcher and lead author of the study, Nicole Carnt from the Institute for Eye Research, Sydney.

The results show the deficiencies in the much publicized Andrasko Staining Grid which looks at corneal staining after the lenses were worn for only two hours.

“Short term testing of lens and solution combinations, based on the extent of staining after 2 hours to predict long-term clinical success, has been widely publicized. The problem is that it does not reflect performance over time.”  “The IER Matrix study asked two questions: how can the practitioner differentiate this type of staining from other corneal interactions that occur with lenses and how well can the IER provide guidance on the best choice of solution-lens combination?” she added.

The IER Matrix Study defines Solution Induced Corneal Staining (SICS) in order to avoid confusion with other corneal staining phenomena. The classifications are released in the Spectrum paper and on the IER website (www.ier.org.au). “There are two manifestations of solution related staining, ‘diffuse punctuate’ and ‘peripheral annular’ and they are easily differentiated from corneal staining resulting from other causes” said Carnt.

The study reveals that each solution-silicon hydrogel lens combination presents a unique ocular situation; some causing staining, in a high percentage of wearers, others causing very low staining, whereas, hydrogen peroxide causes almost none. “SICS staining hardly occurs at all when hydrogen peroxide is used as the disinfecting solution” said Carnt.

The study was funded by grants from the Institute for Eye Research and CIBA Vision.

“This paper presents the first 16 out of a possible 36 combinations of solutions and lenses and subsequent reports will provide details of solution-lens combination in terms of physiological responses, comfort and adverse event rates,” said Head of Clinical Research at the Institute for Eye Research, Dr Vicki Evans. “We are keen to see all the IER Matrix results; it’s a major investment towards providing valuable information to practitioners so that they can make the right choices”.

Speaking on behalf of the Institute for Eye Research, CEO Professor Brien Holden said, “Corneal staining is the primary in-practice tool for evaluating the state of the corneal epithelium. It is an IER core responsibility to advise practitioners on the importance of our observations in the research clinic. We know that wearers with SICS have a higher risk of discomfort and infiltrates but we are disturbed that some have drawn conclusions between SICS and microbial keratitis. This is quite inappropriate,” he added.

“IER researchers offer the opinion based on previous long-term IER studies in Australia and India with extended wear of silicone hydrogel lenses that there is no evidence of any relationship between the levels of non solution related type of staining in these studies for the 10 patients that sadly went on to have microbial keratitis” commented, Senior Researcher for IER, Professor Deborah Sweeney.

However, Sweeney agreed with Professor Mark Willcox, Chief Scientific Officer of the IER, when he said, “microbial keratitis is caused in contact lens wearers when large numbers of pathogenic bacteria get access to a cornea compromised usually by a direct epithelial breach. There is no evidence that SICS causes such a breach but the possibility does need to be studied”.

Professor Holden summarized some of the current dilemmas in lens care: “The solutions manufacturer has a tough job. On the one hand the market wants comfort but microbial efficacy and safety come first. Recent events have shown us the folly of not adhering to that fundamental principle. However this study shows us there is yet another dimension, the ocular consequences of lens-solution interactions.”

Holden continued: “Perhaps the most important result of the data released by the IER so far is contained in the conclusion of the Spectrum IER Matrix paper which concludes; ‘While the results of longer term clinical studies, such as the IER Matrix, are useful in minimizing SICS by choosing the appropriate combination, currently the only way to virtually eliminate solution-induced corneal staining with silicone hydrogel lenses is to use hydrogen peroxide disinfection.’ ”

--ENDS--

CORRECTION: In the published IER Matrix paper on Solution Induced Corneal Staring with Silicone Hydrogel lenses, the rate of SICS for the PureVision® (Bausch & Lomb, Rochester, USA), OPTI-FREE® Replenish® (Alcon Laboratories Inc, Fort Worth, USA) combination was reported as 20.9% however it should be noted that "all people wearing this combination had not completed the full three months", was inadvertently omitted from the paper by the authors. Since submission for publication in Contact Lens Spectrum (September 2007 edition), all remaining wearers have now completed the full three months wear of the combination and the rate of SICS was 14.2%.
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Reference:
Corneal Staining with Various Contact Lens Solution - Silicone Hydrogel Lens Combinations and its Significance: The IER Matrix Study
Carnt NA,  Willcox MDP,  Evans VE,  Naduvilath TJ,  Tilia D,  Papas EB,  Sweeney DF,  Holden BA
Contact Lens Spectrum, September, 2007

Further information
Tables relating to this article and the pictures defining SICS are available on the IER website (www.ier.org.au). For more images, interviews and further information please contact Stephanie O’Connell, Institute for Eye Research
T: +61 2 9385 7252  M: +61 439600312    E: s.oconnell@ier.org.au