Say Hi to SiHy

Posted on May 12, 2011 · Posted in Contact Lenses, Eye Health

Today’s patients have more options than ever before when it comes to choosing a method to correct their vision.  Most know of glasses and traditional contact lenses, but newer technologies like LASIKCorneal Refractive Therapy, and silicone hydrogel contact lenses offer customized solutions and freedom from the traditional forms of vision correction.

What’s this silicone hydrogel thing, you ask?  Silicone hydrogel, or SiHy as it is affectionately known, is a super-breathable material of which the majority of new contact lenses to the marketplace are made.  Most of the lenses made from this material have achieved extended wear designation by the FDA.

Let’s define contact lens wear terms before we move any further:

  1. Daily wear: you wear during the day, remove at night
  2. Extended wear: you wear during the day, leave in at night

Lenses have typically fallen into one of these two categories based on something called oxygen transmission, or, their ability to allow oxygen to reach the surface of the eye.

Why is oxygen important to the eye?  (you ask such good questions)  Let’s just say that oxygen to your eye is like spinach to Popeye.  With it, the eye can keep its defenses up and fight off infection.  Without it, the guards take a bit of a nap making it much easier for bacteria, fungi, or other organisms to infect the eye.

Extended wear contact lenses have been around for 30+ years, but early adopters experienced a significant risk of infection.  This ranged from an annoying case of conjunctivitis/pink eye to potentially blinding conditions like corneal ulcers.  Enter silicone hydrogel.  By allowing 7-8x more oxygen through the contact lens to the surface of the eye, the incidence of infection decreased.  Today’s silicone hydrogel contacts are approved for anywhere from 6 to 30 days of extended wear.

It should be noted, though, that just because a contact lens is made of silicone hydrogel material doesn’t mean that the wearer is immune to infection during extended wear. Sleeping in any type of contact lens carries greater risk than taking them off overnight.  That’s a fact.  But newer materials make it a safer option than it used to be.

Here’s the bottom line: contact lenses are medical devices and should be treated as such.  If you are sleeping in your contacts and you haven’t discussed this with your doctor, stop.  Call their office and see if extended wear is safe for you, if your lens is approved for extended wear, for how long, and what precautions you should be aware of.  Your doctor will not get mad at you for expressing a desire for a more flexible form of correction.  (I state that because new patients to our office sometimes are reluctant to share that they sleep in their lenses almost expecting some negative reaction on our part.  This is critical information for you and your doctor to discuss so do not hesitate to share it!)  

In the end, it’s your doctor’s job to prescribe the best correction for you health-wise and convenience-wise.  Newer contact lens materials make meeting both of these criteria easier.

If you have questions/comments/concerns, let’s discuss them.  Feel free to comment below or on our Facebook page.