Tuesday, July 11, 2017

Acuvue Contact Lenses History and Introduction

Hey guys, I'm here to give you guys a short history of Acuvue Contact Lenses and will review the contact lenses in a following post. Please view my article on which modality (Dailies, Bi-weeklies, Monthlies) to choose which lens best fits your style when picking contact lenses. We will be looking at

Dailies
- 1-Day Acuvue Moist (Astigmatism)
- 1-Day Acuvue Define (color contacts)
- 1-Day Acuvue Moist Multifocal
- 1-Day Acuvue TruEye
- 1-Day Acuvue Oasys (Astigmatism)


Biweekly
- Acuvue Oasys (Astigmatism)
- Acuvue Oasys Presbyopia

Monthly
- Acuvue Vita

First a little history of Acuvue. Acuvue first mass-marketed disposable contact lenses in 1987 under the name ACUVUE Brand Contact Lenses.

In 1995 they created the world's first daily disposable. It eliminated the eed to clean and store lenses as they were replaced with a new steril pair every day.

In 1997 they introduced UV protection to all of their lenses, which to this day many popular lenses still do not have.

In 2005 the Acuvue Oasys brand contact lens was developed and was marked as a 2 week lens. It incorporated Hydraclear Plus, technology for increased moisture-wetting ability. They also use an Accelerated Stabilisation design technology instead of a weighted ballast design (thickening the bottom of the lens) to more quickly rotate the lens into place for astigmatic patients where the rotation of the lens is a concern.

In 2006 the 1-day Acuvue Moist lens was created. It included Lacreon Technology that embeded water-holding ingredients to mimic the natural state of the eye.

In 2008 1-day Acuvue TruEye contact lens was introduced. It was their first daily lens to use silicone hydrogel polymer allowing for much better breathability with a Dk of 100. It included Hydraclear Technology similar to the one in Acuvue oasys.

In 2014 1-day Acuvue Define was introduced to western countries from redesigns from Korea.

In 2015 1-day Acuvue Moist multifocals were intoduced

In 2016 Acuvue intorduced their first monthly lens Acuvue VITA

Also In 2016 Acuvue introduced their latest brand of dailies, Acuvue Oasys 1-day. They are made of Silicone Hydrogel material like Acuvue TruEye allowing for greater breathability with a Dk of >100. In Q2 of 2017 they added Astigmatism correction to their line.

Sunday, July 9, 2017

What type of contact lenses should I get? Dailies vs Bi-weeklies vs Monthlies

Which type of contact lens is right for you, dailies, bi-weeklies, or monthlies? I get asked a lot about the differences and benefits of different modalities of contact lenses.

Lets start with dailies. With dailies, you wear them for one day and then you throw them away. There is no messing with cleaning solutions or cases, which does help a bit with costs, up to $90 in savings per year. Dailies are in general more expensive than either bi-weeklies or monthlies. It will run you usually up to $200 extra per year. The bottom line with dailies is the health benefits. When you wear your lens, dirt and other debris can get trapped on your lens. Also, you are constantly shedding cells, oils, etc. that can also get stuck in the pores of the lens. Any contact with contaminated water, dirty fingers, etc. can also introduce microbes onto the lens. This is where things get dicey, and if the lens is improperly stored and sanitized, colonies can grow on the lens and can infect your eye with re-wear. Dailies can benefit as throwing them away at the end of the day does not allow any buildup.

When I prescribe contact lenses, I usually ask them what their work and hobbies are. If it includes many out door activities, l would strongly suggest dailies to them. When playing a sport, a lot of dust can be kicked up and fly into your eyes. Rubbing them and then soaking them overnight solution may kill germs but it does not do much to remove the dirt on your lens. If the solution also does not kill enough germs it can also grow in your eye and cause more issues. With the release of hydrogen peroxide cleaning solutions, I do feel more comfortable about the sanitization of the lenses, as hydrogen peroxided can kill most of the microbes.                                                                      

If you are also a temporary contact lens wearer, it will be much cheaper and healthier to buy fewer dailies and use them say on the weekend only, or when you need them.

With Bi-weeklies, you throw the contact lenses away every two weeks. These lenses are good for the semi active people. If you participate in outdoor activities once or twice a week, then this lens may be good for you. If you have mostly a desk job and are at the computer most of the time, you will probably not accumulate as much dust or microbes on your lens as compared to someone more active. These lenses will run you a little cheaper but you are going to have to pay about $90 more a year for contact lens solution. I would definitely recommend the hydrogen peroxide solution for disinfection as it is much better for sanitizing the lens.

This brings us to our last modality, monthlies. I usually recommend monthlies if cost is an issue or you have a rather sedentary life style. If going outside isn't really your thing and you would rather spend your free time watching tv or playing video game. Then these lenses should be fine for you. It is important to know that you can still infect your lenses from the natural bacterial flora on your eyes or from rubbing your eyes after touching a contaminated surface. You still have to be careful with disinfection and I would recommend the Hydrogen Peroxide here as well.

So whats the trade off with dailies vs bi-weeklies and monthlies?

There is still one thing I do have to mention here and that is oxygen content. You will see me revisit this issue every time I talk about contact lenses. With dailies, most of the cheaper dailies still use hydrogel technology. As much as I have touted the benefits of all dailies, they still do not provide as much oxygen to the eye as silicone hydrogel. This is fine for those with low prescriptions. But for those with higher prescriptions, greater than +/-4.00 to +/-5.00, the lens becomes thicker and the eye receives even less oxygen. This is where I would recommend a silicone hydrogel lens. Most daily silicone hydrogel lenses are premium and very expensive, these lenses are the best contact lenses you can get as they are the healthiest for your eyes. But where cost is a concern, it may be better to go for a biweekly lens if you have an active lifestyle.

Monday, June 26, 2017

Are Hubble Contact Lenses really Worth trying? An Optometrist's (eye doctor's) perspective

I was sitting on my couch and came across a commercial for Hubble. It talked about a new dailies contact lens that harped mainly on the fact about how cheap the lens was. Very quickly a red flag went off in my head. You've probably seen the commercial and I'm sure millions have seen it too. This led me to do some digging about the contact lens.

History

First let me tell you a little about the history of contact lenses. The first contact lens was a scleral lens made of blown glass by German glass blower F. E. Muller. It was a large lens that rested on the white less sensitive part of the eye called the sclera. It vaulted over the clear part of the eye called the cornea. A dextrose solution was used as a medium in between the cornea and the lens. It was large and could only be worn a few hours at a time. These lenses persisted until the 1930s when PMMA a special type of plastic was invented. With this invention, a smaller contact lens that rested on cornea was produced. The main issue with this type of lens was that it allowed less oxygen to pass through to the cornea which introduced a host of issues. The cornea is a living tissue and is one of the most important structures of the eye as it allows light to pass through into the eye. It does not have blood vessels to deliver oxygen to it, because blood would block your vision. Instead the cornea, especially the surface, gets most of its oxygen from the air. This is quantified by the oxygen transmissibility or (Dk) of the lens. While Dk is more commonly used to judge lenses, the actual transmissibility of a lens depends also on thickness of the lens which increases with higher powers. By slapping a large piece of plastic on your eye you are essentially choking your cornea by blocking the oxygen that is necessary for your eyes.


PMMA essentially allowed no oxygen to get through to the cornea and had to rely on oxygenation through tear exchange. This led to the creation of  ridged gas permeable (RGP) lenses in the 1970s which improved oxygen delivery to the cornea. While the RGP was being developed, the first soft lens was created in the 1960s. It was made of a softer hydrogel material that was much more comfortable that the ridged lenses. These lenses had a Dk of ~9. Bausch and Lomb was the first company to produce these lenses. Further advancements in soft contact lens technology focused on increasing the oxygen permeability through the polymer material. Hydrogels today have a Dk upwards 25. The next largest advancement of soft lenses was the development of silicon hydrogel. These lenses allowed for a much higher Dk, upwards of 100.

This leads me to the new Hubble lens. Can I recommend this lens? In short, No. Why? Lets analyze this lens and then compare it to the competitors.

Oxygen Permeability (Dk)

From looking at the history of the contact lens mentioned above, this is one of the most crucial factors when looking at a contact lens. Lenses with lower Dk "choke" and kill the cells in the cornea called the epithelium. The epithelium is one of the most important layers as it is the skin of the cornea. This creates little open wounds on the eye which we can see as bright yellow dots when stained with yellow dye. These open wounds allow for bacteria, virus, fungus, or other microbes to invade the eye. If serious enough, they may cause irreversible blindness or even death as fungi can eventually spread from your eye to your brain. This is why oxygen permeability is extremely important for the health of the eye. Another issue that this causes is that when the cornea is choked, it has to find another oxygen source. Blood vessels start to grow from the white part of the eye on to the clear part of the eye. If not controlled, it can lead to cloudiness of the cornea and eventual blindness. Hubble lenses have Dk from sources ranging from 18-21. Acuvue 1-day moist on the other hand has a Dk ranging from 25.5 - 28. Dailies Aqua Comfort Plus has a Dk of about 28. They are all based off of hydrogel gel polymers, and already with such a low Dk, its best to get as much Dk as you can get.


Material / hydrogel design (metafilcon A)

As you can see already not all Hydrogels are created equal. They vary with oxygen permeability by the water content of the lens. The more water content of hydrogel lenses the more oxygen is transmitted. Metafilcon A is a much older type of material that was used in lenses such as Frequency 55 which, made by Coopervision, is now discontinued. Many of the lenses that optometrists now prescribe are of newer material such as etafilcon A in 1 day
moist and nelfilcon A in Dailies Aqua Comfort Plus. Hubble is pretty much rebranding 15-20 year old lens and selling it to you as the next "new" thing to the unsuspecting consumer. "New" is not always better. Do your research. Reputable companies like Vistacon, Alcon, and Coopervision will always improve on their material which is why frequency 55 was discontinued.

Bottom line... Do they really care about the consumer's health and/or vision?

The old saying holds true in this respect you get what you pay for. But when it comes down to your eyes and vision, is this something you really want to take a risk with? You spend maybe an hour or two watching cable TV and maybe 3-4 more on your phone or at the computer. Yet you are willing to spend over $1000 on your cell phone bill, $500-$600 on your cable bill, and another $500-$600 on your internet bill. How often on the other hand do you use your eyes? I'll give you a hint.
Its pretty much every single waking second of your life. In fact you have to use your eyes to watch tv, look at your phone, and to look at your computer. Why do you neglect your eye's health? Whats a few hundred dollars a year to make sure your eye health is protected and your vision is the best it can be?

By using cheaper material for the sake of cutting costs, this company Hubble is gambling with the health of your eyes. They dont care about you and is devaluing the importance of eye health to save you a couple dollars. As health care professionals I cannot harm my patients by prescribing them this lens when I know that there is something better.

I will leave you with a first hand experience about this lens from my girlfriend who is an optometrist as well. She had a patient come in saying that she had ordered these Hubble lenses, but had blurry vision through them. My girlfriend did a refraction on her patient and found out something completely startling and unethical about this company. Her patient was found to have a high astigmatic prescription. Hubble did not have astigmatic lenses at the time and instead gave her a spherical lens without letting the patient know. Of course she ended up not being able to see out of them and thus had to return for another eye exam to get another pair of lenses. Hubble did not even have the decency to let her know that they did not have a lens to fit her needs. This just shows the greed of the company and how they only care for themselves and not the consumer.



Thursday, June 22, 2017

A little about me...

Intro...
So you're here to learn about eyes! I am a recent graduate of Optometry school, and I am creating a fun blog to share with you everything I've learned about this 24mm diameter sphere during my 4 years in school. This blog is going to be about eye care including what its like to get an eye exam to my advice on some common problems that I see and even some interesting uncommon problems that pop up once in a while. I will also try to provide the latest news regarding interesting things about eyes that I have found, and my opinion about it.

A little (more than you probably want to know) about myself...

I grew up in the small town of Chapel Hill, NC. Its not as small as some of the towns you've heard of where there is only one street light, but with a population of ~50,000, it's nowhere as large as the metropolitan cities you commonly hear of. As a southerner, I grew up loving sweet tea, fried chicken, and grits. I had a slight southern twang, as my Californian friends would later point out, and would litter my dialogue with a "y'all" here and a "dangnabbit" there (kinda kidding about the latter), as well as cuttin' the "g" off all my present participles. As an Asian, I grew up learnin' how to use chopsticks (sometimes using them to pick at the pieces of fried chicken), eatin' bowls of rice for dinner, and studyin'... a lot... As disparate as these cultures may have been, they both taught me the true value of being a being an affable and virtuous person by respecting your elders and friends, holding open the door for the people behind you, and going out of you way to help someone in need. Both of these cultures have shaped me into the person I am today and I have to say, I am very proud of my southern and Asian roots.

As for my career history, I went to the University of North Carolina at Chapel Hill (Go Heels), where I majored in Biomedical Engineering. What is Biomedical Engineering you may ask? Its a field where we design medical equipment such as x-ray machines and prosthesis for those who have lost limbs. As much as I loved research and design, much of my days were spent alone in the lab soldering circuits or the library. I craved more social interaction and so I looked into the medical field for a future profession. The one profession that I constantly came into contact with through out my life was Optometry. I've always had problems with my eyes, and having a relatively high prescription I would go every year to get new glasses or contact lens prescriptions. It was one doctor's trip I actually didn't mind going to, as I always had some trepidation going to the dentist. My doctor would always take cool pictures of the inside of my eyes and explain to me what he was seeing. I asked to shadow him and that was when I fell in love with the profession. Optometry drew a lot of similarities to the problem solving nature of engineering. You are presented with a problem and through research you design a solution to the problem. Often times you had to think outside the box to design a solution that best fit the patient.

I eventually applied, matriculated, and graduated from Optometry school in southern California. Now I am a fresh graduate with a wealth of information to provide to y'all. And now, on to the good stuff...

About me

A little about me...

Intro... So you're here to learn about eyes! I am a recent graduate of Optometry school, and I am creating a fun blog to share with you...