Silicone Hydrogels: the rip-off.

daysoft+promo+shoot+18.3.14-11-3131097459-ORESIZEMarch 2017.  One of the most frequently asked question I still receive is about Silicone lens material verses Hydrogel lens materials so here is an updated summary.

Silicone lens materials were developed to allow sufficient oxygen to reach the surface of the eye when the eye is closed e.g. in sleep.  But  there is a fundamental problem affecting the eye-health when ANY lens is worn over-night.  It was discovered, yet again, that no-one should sleep in any contact lens, Silicone or otherwise.

The Silicone-mad  scientists had developed a material at great expense to solve one problem only to be blocked by a much bigger one.

So, what was to be done with Silicone?  Rather than put millions of £/$ of research in the bucket (embarrassing and share-holders don’t like boobs) it was decided to market this material for daily-disposable contact lenses even although it provides no material benefit but up-selling the lenses (ie charging more) could be a great profit generator.

Daily-disposable lenses are the safest modality and when made from traditional hydrogel materials with a mid-water content e.g. of 58%,  provide all the oxygen required for healthy eyes.  There is zero corneal swelling when the material Oxygen Transmissibility is 20 or above.  Hydrogels are softer and better generally as the research papers below illustrate.

Ron 02082017

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 17 April 2015.  Editor of OPTICIAN Magazine, Chris Bennett, states in his Editorial; ” The latest contact lens launches are Silicone-free”.     For example, the two latest contact lens launches by J&J are based on its Hydrogel material not its Silicone Hydrogel material. The myth is being exposed.   Now read on ….

Your eye-sight is precious so make sure you wear contact lenses that allow the necessary flow of oxygen (20 Dk units) to your eyes but make sure no one hits your pocket with a myth!

Silicone hydrogel (SiH) contact lenses can have flow rates 10 times the recommended minimum of 20 (ie 200 Dk units) but the actual oxygen getting to the endothelium (where it is used by the eye) is exactly the same as for a lens with a Dk of 20.

Don’t fall for the myth which encourages you to pay more for something giving no additional benefit. daysoft® lenses with a Dk of 26 hit the bulls-eye.

There is also a Silicone side-effect … they are ‘harder’ and it is now of concern that this causes ‘mechanical complications’. A recent round-table discussion conducted by Optician magazine for opticians resulted in these comments: I fit a lot of daily disposables lenses and we’ve not been happy fitting SiH daily disposables. We see lid changes after a year or two. We’ve all patients who we’ve put into SiHs and for one reason or another it hasn’t worked so we’ve gone back to hydrogels. …. in daily disposables the SiHs are hit or miss in the comfort factor.”

The bottom line …. SiH lenses have not increased the market despite huge research expenditures.

daysoft® contact lenses contain no silicone. They provide all the oxygen required for normal daily-wear and are uniquely affordable and soft for great comfort.

Why pay £44 a month for 1-day silicone lenses? Switch from today,27th May 2013 to daysoft® using www.daysoft.com for £12.48 a month (2 Boxes of 32 lenses delivered now).

BACKGROUND ANALYSIS

Recent Scientific Papers (2012/2013)

Complications from SiH wear have continued to be reported, despite significant efforts to reduce stiffness and improve wettability of the materials.Reporters now conclude that SiHs have not grown the market, have not improved comfort and due to higher modulus and reduced drape can mechanically damage the surface of the eye.

The 2013 paper, Mechanical Complications Induced by Silicone Hydrogel Lenses, cites the varied complications as:-

  • Mucin Balls (which cause dents in the corneal surface)
  • SEALs ( lesions caused by the stiff lens abrading the eye)
  • Corneal Epithelial Erosion ,Induced Papillary Conjunctivitis, Conjunctival Epithelial Flaps, Lid Wiper Epitheliopathy and Meiobium Gland Dropout

It is important to note that such complications occur with SiH lenses irrespective of wear modality or type of cleaning solution used. In a 2012 paper Brien Holdenreports that TruEye (Narafilcon A) Daily Disposable lenses displayed higher levels of mechanical complications than a conventional hydrogel lens. Even the state of art SiH material is still prone to complications, and the jury remains out on the longer term adverse effects.

Other Recent Scientific Papers (2012/2013)

Complications from SiH wear have continued to be reported, despite significant efforts to reduce stiffness and improve wettability of the materials. Reporters now conclude that SiHs have not grown the market, have not improved comfort and due to higher modulus and reduced drape can mechanically damage the surface of the eye.

The 2013 paper, Mechanical Complications Induced by Silicone Hydrogel Lenses, cites the varied complications as:-

  • Mucin Balls (which cause dents in the corneal surface)
  • SEALs ( lesions caused by the stiff lens abrading the eye)
  • Corneal Epithelial Erosion ,Induced Papillary Conjunctivitis, Conjunctival Epithelial Flaps, Lid Wiper Epitheliopathy and Meiobium Gland Dropout

It is important to note that such complications occur with SiH lenses irrespective of wear modality or type of cleaning solution used. In a 2012 paper Brien Holden reports that TruEye (Narafilcon A) Daily Disposable lenses displayed higher levels of mechanical complications than a conventional hydrogel lens. Even the state of art SiH material is still prone to complications, and the jury remains out on the longer term adverse effects. You might also want to read the thread The Truth about Silicone Hydrogel Lenses http://studymyhealth.wordpress.com/2008/05/18/silicone-hydrogel-contacts-the-new-wave-of-high-oxygen-high-discomfort-lenses/    Also, “A Model of Oxygen Flux Through Contact Lenses”.   Noel A Brennan, MSc Optom, PhD, FAAO

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