Letter: Permeability isn’t everything
Author: Ron Hamilton, executive chairman
In the report relating to Coopervision’s inaugural European Media Summit (Optician, 7.12.18) Chris Bennett, editor, poses the question: ‘Fitting wearers with the healthiest contact lens option is what everyone wants so why doesn’t it always happen?’ In this letter I would like address what I believe is the more fundamental question: ‘What is the healthiest contact lens option?’
Marcella McParland, Coopervision’s director of professional services for European, Middle East and Africa region, is reported as accepting that daily disposables are ‘driving growth’. This answers part of the question, ie that the daily disposable modality is now widely, if not universally, agreed to be the healthiest modality. Those in the industry who follow such matters now accept this conclusion because it is based on a massive body of evidence reported over 25 years of independent research and practical field-experience. Daily disposable wear is the ‘healthiest modality’ … full stop.
However, in the article this well-established position is ‘embellished’ to become: ‘The clear message from the summit was that daily disposable SiHy lenses are the most healthy option so McParland concluded by outlining Coopervision’s three brands of daily-disposable SiHy lenses which, she explained, were breathable, had a high water content and offered UV protection.’ What is missing from this statement is any evidence to support the incorporation of silicone hydrogel material. The summit message is not evidence.
SiHy material was developed for extended wear lenses by giving enough ‘breathability’ performance, to equal that of ‘no-lens’ wear. It looked like a breakthrough in material science but the extended-wear modality for which SiHy was developed raised unanticipated serious eye-health risks during wear. This clearly demonstrated, yet again, that, even enhanced ‘breathability’, is not the only, or even main, factor relating to eye-health. SiHy material used in extended-wear contact lenses, originally seen as ‘the holy grail’ of contact lens wear, failed catastrophically and in a not dissimilar to the failure of high-water extended-wear contact lens wear heavily promoted by Coopervision in the 1980s.
The massive development investments made in applying SiHy materials to extended-wear contact lenses have been wasted, unless, some have thought, the new ‘holy grail’ would be daily-disposable SiHy lenses? This attractive, but misplaced, logic led to the idea that SiHy materials, if used in daily-disposable applications as a more ‘highly breathable’ daily-disposable, would now give the ‘healthiest contact lens option’. but there is no evidence to prove that it gives any better eye health performance than well-established hydrogel materials. ‘Selling’ such benefits without supporting evidence is mis-selling, especially when accompanied by the much higher (over three times) prices charged to wearers for SiHy material lenses.
Once again, the contact lens industry is in danger of becoming transfixed by oxygen permeability and equating that to ‘being healthier’. This oxygen obsession is overlooking the facts that contact lens health issues are much more complex and that they have already been met by existing, widely used, well proven, well researched, much lower cost, softer, more comfortable hydrogel materials which provide all the oxygen required for safe daily wear.
Daysoft Limited: Cover story
Optician is delighted to point out that the wraparound cover material used on last week’s issue promoting Johnson & Johnson’s Contact Lens Recycle Programme was made from a recyclable and biodegradable polyester known as PETG. While having many of the aesthetic properties of other clear plastics this material was sourced because it is biodegradable and recyclable. This enabled attention to be drawn to the important topic of recycling without contributing to the problem.