Silicone Hydrogels - The UK Experience

Lisa Keay - BOptom Hoons FAAO
Lisa Keay graduated from the University of New South Wales (UNSW) in 1993 and worked briefly in private practice in Australia before joining the Cornea and Contact Lens Research Unit (CCLRU) at UNSW in Sydney. She worked at the CCLRU for 3 ½ years as a Clinical Optometrist and Manager of Clinical Research. Her principal areas of research were extended wear of silicone hydrogel contact lenses, the tear film and the biocompatibility of contact lenses. She has just returned from 2 years in the UK, where she continued to work in contact lens research as a sessional optometrist at Moorfields Eye Hospital and as a consultant
lecturing on silicone hydrogel extended wear to practitioners .

Extended wear, popular in the US, has not been a mainstream component of contact lens practice in the UK for some time, following experiences with extended wear in the 1980's. Extended wear was prescribed quite extensively in the UK prior to the publication of the link between corneal infections and extended wear^1,2. A lot of critical research on risk factors for microbial keratitis originated in the UK, identifying issues such as infrequent³ and inadequate lens disinfection⁴ and extended wear itself³. It is a reflection of the awareness of these facts amongst contact lens practitioners that extended wear of traditional materials was effectively disbanded in the UK, and during the 1990's the extended wear UK market shrank to a negligible proportion of lens fits⁵ .

The prospect of extended wear arose again with the introduction of silicone hydrogels in the UK in 1999. PureVision by Bausch and Lomb was released in May 1999, followed by Focus Night & Day by CIBA Vision in November. General awareness of the risks of extended wear with traditional materials and the number of experts amongst the professional community in the UK predicted a cautious reception for these new products. This caution is not only confined to practitioners. Following publication of a study in 1999, re-affirming established incidence rates for microbial keratitis⁶, the dangers of extended wear featured once again in the mainstream media, alarming the general public.

With this EW history, the use of silicone hydrogels in the UK has therefore been monitored with great interest. Since their introduction, silicone hydrogels have slowly but steadily gained market share, primarily among existing wearers. Eurolens annual surveys of the CL market in the UK found extended wear increased slowly at first with 3.6% of soft lens re-fits in 2000⁷, but increased significantly to 12% of soft lens re-fits in 2001 . Extended wear can now be considered a mainstream contact lens modality in the UK for the first time in over 10 years, outpacing tinted lenses, multifocal lenses and coming close to the market share of toric contact lenses⁸.

It is interesting to speculate on what proportion of practitioners are fitting silicone hydrogels in the UK. In Australia, where extended wear has reached a high level of penetration (16% of CL fits), it appears that there are a large number of practitioners fitting some extended wear, rather than there being a small number of extended wear enthusiasts⁹. A similar trend has been observed in the UK (PB Morgan, 2002, Personal communication). A survey of the audience at the British Contact Lens Society meeting in 2000 found that 37% of the audience had fitted silicone hydrogels but had fitted less than 10 patients¹⁰. A more recent survey published in 2001 indicated that up to 65% of UK practitioners are now fitting silicone hydrogels, although around half had fitted fewer than 10 patients¹¹.

This leads us to ponder the reasons for not fitting silicone hydrogels. In an audience survey of the British Contact Lens Association in 2000, those not fitting silicone hydrogels were hesitating largely due to concerns over microbial keratitis (2/3 of responses) but also due to concerns over other possible adverse responses. In the more recent survey¹¹ those not fitting specified that they needed more clinical information before recommending silicone hydrogel extended wear (49%). In a similar vein, around 1/5 of those not fitting were not confident in managing extended wear. A practice-based clinical trial of silicone hydrogel extended wear¹² demonstrated increased acceptance of silicone hydrogel extended wear with experience. By end of a 3-month study, where 10 patients were fitted per practitioner, 89% felt confident with the new modality. Generally practitioners rated the lenses highly for vision, fit and overall performance; and patients for comfort, convenience and overall satisfaction. Positive experiences amongst practitioners with silicone hydrogel extended wear will be the key factor in ensuring continued market growth of these lenses.

Brian Tomkins is an example of an independent UK practitioner who has embraced the new modality. Brian has fitted over 250 patients with silicone hydrogels, and has generally found the lens successful: "Great for my dry eye patients and my 30 night CWs are all over the moon as they have 'new eyes'."

The decision to fit extended wear has meant a radical change in policy for most practitioners in the UK. This is in contrast to the US where extended wear already comprised 12.5% of contact lens market prior to the introduction of silicone hydrogels¹³. Practical issues such as not being able to provide 24-hour care and extended wear being against the policy of the practice accounted for about 1/3 of reasons for not fitting silicone hydrogel EW in a survey of UK practitioners¹¹. Members of a BCLA audience reported that peer-reviewed journals and conference speakers most influenced the way they practice (combined 87% of respondents), while there was skepticism about company data and company sponsored publications. Multiple practices, which cover a large portion of primary eyecare in the UK, have the ability to make a significant impact on the uptake of extended wear by virtue of their large buying power. To date most of the multiples have addressed the issue of introducing extended wear into their stores. Boots Opticians began to actively prescribe both brands of silicone hydrogel lenses in November 1999 after in-house clinical trials. Specsavers were the first group to offer an 'own brand' product with Easyvision All day-All night lens (Focus Night & Day) also in November 1999. Representatives from both Dolland & Aitchison and Vision Express confirmed that in-house trials would influence the decision whether to embrace EW¹⁴.

Specsavers now has over 2 years experience with silicone hydrogel extended wear and reports a high degree of success. Brian Kingsley from Specsavers says that they now have 23,000 patients in lenses and that the "general impression is excellent with a steady growth in new fits. Our practitioners love the lens and a number wear it." Specsavers has also reported benefit from intensive education of practitioners prior to introducing extended wear. This was in the form of lectures by independent speakers on clinical performance of silicone hydrogels. The format was such that practitioners were able to address their concerns regarding clinical performance and management issues. As expected a large number of questions centered on the risks of microbial keratitis and practice strategies to minimize contact lens contamination.

An enormous effort both in research and development and commitment by contact lens distributors has been expended on re-visiting extended wear. It was interesting to note that in the survey by McParland¹¹, a small proportion of UK practitioners (<10%) reported that they felt there was no demand for extended wear. This is in contrast to surveys of contact lens wearers, which report a high level of interest in extended wear. CCLRU surveys show 68% of patients surveyed are interested in extended wear (n=1473). Practitioners can take solace in the fact that interest in extended wear is linked to practitioner endorsement. Bergenske¹³ reported 25-30% interest in extended wear rising to 60-70% with practitioner recommendation.

The need for convenience amongst consumers is major factor impacting contact lens wear. A UK survey (n>1000) found that 26% of contact lens dropouts reported that contact lens wear required too much time and effort¹⁵. These concerns constitute a significant financial impact to the contact lens industry. It has been estimated that there are 2.1 million annual drop-outs in the US which translates to approximately 60% of actual wearers¹⁵. Extended wear may partially address the shortcomings of contact lenses. Of those who have discontinued lens wear and never resumed, concerns which would influence their decision to resume lens wear, were primarily discomfort (54%) but also convenience issues with 11% reporting the desire for continuous wear and 7% simpler care and maintenance¹⁶. This was further supported in another UK survey of contact lens wearers where 23% of respondents wanted longer wearing times and 1% less cleaning¹⁷.

Since their introduction, there have been television advertising campaigns highlighting the convenience of these new products. The majority of reasons for UK practitioners fitting extended wear are patient request and desire for 24 hour vision¹¹. While the impact of increasing consumer awareness is uncertain, one could only speculate that there is some benefit in stimulating the sluggish contact lens market in the UK and prompting patients to ask their practitioners about these new products. The consumer-driven society in the US has a far higher penetration of CL use with an estimated 15% compared to just 7% in the UK⁵.

It is still early days to interpret the success of silicone hydrogels in the UK. Initial assessment indicates that there is significant growth in extended wear and positive feedback from practitioners. In a survey of 500 European ophthalmologists, including 100 from the UK, 65% felt silicone hydrogels represented a significant improvement compared to old extended wear materials¹⁸. Amongst contact lens practitioners, it has been reported that the level of confidence in silicone hydrogel is significantly higher than refractive surgery (87% vs 36%) and 9/10 practitioners would recommend silicone hydrogel extended wear over refractive surgery¹¹. It is with anticipation that we wait to see the full impact of silicone hydrogels on contact lens practice and vision correction in the UK.