Quality over Quantity.

Not all lenses are created the same — some are actually more breathable than others. In fact, you want to know the oxygen transmissibility or Dk/t value of a lens. This tells you how much oxygen can pass through. Often this depends on the material used.

So, lets take a look at some of the best and worst?

Table information complied from Contact Lens Compendium. (https://contactlensupdate.com/compendium/ca/)

As you can see, the higher the DK/t number— the better— or more breathable a lens is. The type of lens is important too: silicon hydrogel lenses out perform hydrogel ones. Studies recommend we should have at least 25 dk/t in a daily lens to prevent cornea edema (or swelling). When we get cornea edema, overtime, our blood vessels in our eyes will start to grow abnormally to find oxygen. This process is called, corneal neovascularization. When we wear bad contacts for too long, this can cause real damage with time. Sometimes, the damage is not reversible without proper treatment. Complications such as corneal ulcers — a painful bacterial infection that eats into our cornea, and GPC (or Giant Papillary Conjuctivitis) — basically, giant bumps on our eyelids that makes contacts uncomfortable to wear are just some examples.

I CAN’T BREATHE!

Imagine placing a plastic bag over your head for an entire day. This is similar to wearing contacts. Some are more breathable and hold more water content so your eyes won’t dry out. So, the longer you plan to wear your contacts, the more important comfort becomes. As a general rule, a maximum of 6-8 hours of wear is recommended. You should always have back-up glasses for when the lenses come out at the end of the day, and for those rainy days when you can’t put them in. Finally, carry dry eye drops for when the eyes get dry.

YOU PAY FOR WHAT YOU GET?

Check out the worse offenders at the bottom of that list. Let’s choose Hubble. Great brand and idea but it’s using one of the worse lenses on the market. Not only does the lens not meet minimum requirements in Dk/t values (scores an 18 vs a 25 for daily wear). This lens material has been discontinued from the market years ago by Cooper Vision. Since then, Copper Vision has created way better lenses such as their Bioinfinity line. So why are they so expensive? It’s actually not, if you factor in what you’re really paying Hubble for… convenience factor (packaging, delivery, subscription idea) over lens technology. It’s R&D — research and development that goes into creating better lenses. Just like how Apple invests millions of dollars to push out a new iPhone yearly, there’s always newer and better lenses to choose from. You don’t want to be using old technology. Why would you do so here for your eyes? Your local optometrist can recommend the best lens for your eyes and take care of them. Keep in mind, Dk/t value is one criteria, there’s more to assessing which would be the best fit for your eyes.

It AIN'T COMFORTABLE

Dk/t value doesn't correlated with comfort. So, just because you get the highest Dk/t lens, doesn't mean it will be the most comfortable either. Comfort depends on a balance of several lens properties: surface, modulus, and lens design. Basically, all the SiH (silicon hydrogel) lenses provide enough oxygen for daily wear. The higher Dk/t, the stiffer the lens. Too stiff can result in unwanted prescription changes or distortion. Too soft a lens can prevent lens movement and tear exchange. Surface treatments on the lenses also important for comfort because it affects lubricity (mechanical rubbing from friction). And finally, lens design-- the way it fits and shape to our cornea.

What about fit?

Not all eyes are created equal, neither are lenses. Some fit better than others. You can buy a great shoe, but if it doesn’t fit, it will never be comfortable, no matter how great they are. When you wear them long enough, it just becomes uncomfortable and won’t allow you to perform well. Just know that lenses come in different sizes: thickness, diameter, curvature, and materials. This is important for an eye care professional dispensing your lenses to check how a lens fits on the eye and check them over time, as your eyes may change.

Lets talk about Underwear…

Lenses have replacement frequencies for a reason. In school, we had a saying that, you wouldn’t wear the same underwear everyday without cleaning them… why would you wear the same contacts every day without cleaning them or replacing them. 1-Day lenses are for 1 day use, then thrown away. They aren’t built to be used repeatedly. Monthly lenses are good for 30-day use. Lenses must come out of the eye every day and be cleaned in disinfecting solution with digital rubbing. This means, just like you need to rub soap on your hands to remove bacteria, you need to actually rub the lenses before dropping them into your case with solution. Contact lens cases should be replaced with each new bottle of solution or every 3 months. If you use make-up, it should be thrown away every 6-9 months since bacteria can grow in them and infect your eye. Always put your lenses in first before any make-up.

Contacts x Sleep a NO-NO

It’s drilled into every one of my patients, but why can’t we wear them? Studies have shown that the highest risk for infection is sleeping with our contacts. Our tears are so important in protecting our eyes from bacteria, dust, allergens. When our eyes are closed, we are no longer are blinking and creating tears to protect the eye. Instead, it becomes a nice warm bed for bacteria to grow quickly. Since our corneas is such a slippery surface, bacteria has a hard time growing big enough to attack our eyes. When we have contact lens in, it provides a great place for bacteria to latch on and is nutrient-rich.

CDC Corneal Infections Case Report Associated with Sleeping with Contacts: https://www.cdc.gov/mmwr/volumes/67/wr/mm6732a2.htm

ENOUGH SAID.

Contact lenses are great tools to help us see. Just remember... don’t sleep with your contacts, follow the tips above, get great comfortable contacts, practice proper contact lens hygiene, use eye drops when your eyes are dry, see your optometrists regularly for check-ups, and you’ll be off to a great start to maintaining healthy eyes for life. Hope you find this helpful, our eyes are so important. Share with others. Thank you for reading.

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