The Truth About Acuvue 24:31 PM
First off, I don't want anyone to think that I am picking on Acuvue as a company. I wore Acuvue 2's very happily until I got to optometry school. And I thought I was supposed to wear them for a month at a time. I was just like so many of my patients, overwearing my lenses due to poor information. This post is for all of those misinformed people like my younger self, who may be permanently harming their eyes by incorrectly wearing their contact lenses.
IS ACUVUE 2 A HEALTHY LENS?
Yes, when worn properly. If you dispose your lenses every 2 weeks, and do not sleep in them, then Acuvue 2 can be a perfectly healthy lens. Remember, the cornea gets all of its oxygen from the atmosphere, so contact lenses must allow oxygen to pass through. The amount of oxygen passing through to the cornea in an Acuvue 2 lens is 33 Dk/t (this is a unit describing the rate of oxygen passing through the lens). Newer lenses (like Biofinity, Acuvue Oasys, and Air Optix Aqua) have Dk/t values over 100! So as you can see, Acuvue 2 lenses have significantly less oxygen to the eye than newer products. To be safe for overnight wear, studies have shown that lenses have to have at a minimum of 80 Dk/t (and even this shows some signs of corneal swelling the next morning). This means Acuvue 2 lenses are absolutely not healthy to be slept in!
WHY DID MY DOCTOR MAKE ME CHANGE BRANDS FROM ACUVUE 2?
There are 2 reasons that I switch a person from a brand they like:
1) They are overwearing their lenses past the FDA approved wear time. If you are sleeping in your lenses or want to wear your lenses longer than 2 weeks, we have to change to a different contact lens brand and material that is approved and healthy for that amount of wear.
2) They are suffering from damage to their cornea. Some people can wear their lenses correctly, and still have consequences from poor oxygen flow to the eye. Any time I see corneal neovascularization (the growth of blood vessels into the cornea, which is supposed to be a clear tissue) I know that the cornea needs more oxygen than it is getting. Contact lens acute red eye, giant papillary conjunctivitis, and corneal scars are other indicators. See this post for more information.
|Corneal Neovascularization: it looks like chronic redness in the mirror, but under the microscope your doctor can see individual anomalous blood vessels that have entered the clear tissue of your cornea|
I HAVE TRIED OTHER LENSES, BUT NOTHING FEELS AS GOOD AS ACUVUE 2
I hear this all the time from my patients. Acuvue lenses are VERY comfortable, and it can sometimes be hard to find a lens that feels as good. Lenses that have more oxygen to the eye are generally made of a different material called Silicone Hydrogel. In some patients, this material can cause more depositing, making vision more blurry through the day than when they wore their old hydrogel lenses. This only happens to a small percentage of patients, but it is a definite possibility. Almost every patient will experience some "tingling" sensation within the first month or two after changing lenses, but this is actually a good side effect. This tingling means that the cornea is being stimulated by the extra oxygen, and the damaged corneal nerves are regenerating. If you can make it through this transition period, the new lenses are going to be comfortable and more healthy.
TAKE HOME POINTS:
Acuvue 2's can be healthy lenses when worn properly. This means NO sleeping in the contact lenses, and throwing them away every 2 weeks. If your doctor sees signs of corneal damage, a change in lenses might still be necessary. As an optometrist, I want to reassure everyone that we don't have a grudge against your lenses, we just have seen the complications from unhealthy contact lens wear and don't want to see that happen to you!
Many of you may have noticed that back in the early 1990s when Acuvue 2 was FDA approved, it did get overnight wear approval as long as the lens was thrown away every week. That means if you slept in the lens, you had to throw it away after 1 week of wear, not two. Since that time, multiple studies have shown that a lens like Acuvue 2 has too low oxygen transmission (Dk/t) to be safely worn overnight without causing corneal edema (swelling). Doctors no longer recommend any overnight wear of this lens, and instead recommend Acuvue Oasys with weekly disposal if you prefer sleeping in an Acuvue lens.