Hello everyone this is Dr. Audrey Tai, I am a board certified and fellowship trained LASIK and
cataract surgeon, ophthalmologist and cornea specialist. Welcome back to my channel - eye
channel by eye surgeon. In today's video I would like to talk to you about the science
behind the ingredients in artificial tears, these are the over the counter eye drops for
treating dry eye disease. This video will help you understand the differences between different dry
eye drop ingredients, and will help you choose the artificial tears that work best for you.
You can navigate to different categories of ingredients by clicking on the navigation
bar below. If you want to jump right into my list of favorite artificial tears for
treating dry eye disease, you can check out my video on my top five picks of artificial tears,
or if you would like to learn more about the science behind the ingredients
of different artificial tears and why I would recommend certain artificial
tears over other ones, stay here with me and we will go over that in this video.
I have also listed links to my favorite artificial tears in the description below.
To learn more about my practice you can follow me on Facebook and LinkedIn @DRAudreyTai.
And if you have learned anything new from this video, don't forget to like and share this video.
I will also be posting a more in-depth video about the mechanisms of dry eye disease and different
types of dry eyes, so make sure you subscribe to my channel so you won't miss any of my new videos.
Without further ado, let's talk about the ingredients in artificial tears.
The ingredients of artificial tears can be categorized into three groups:
active ingredients, inactive ingredients, and preservatives.
The active ingredients are the agents that have been approved by the FDA to be used
in artificial tears to provide lubrication to the eye. There are three main categories
of active ingredients in artificial tears, astringent, demulcent and emollient.
The most commonly used ophthalmic astringent is zinc sulfate. Two common brands of dry eye
drops that contain zinc sulfate, are clear eyes made by prestige consumer healthcare,
and VISINE made by Johnson & Johnson. zinc sulfate can help reduce the burning and itching sensation
from exposure to the pollutants in the air by reducing the mucus on the surface of the eye,
so it can help reduce some allergy symptoms, but zinc sulfate is not very effective in
lubricating the eye compared to other active ingredients. So it is not a top ingredient in
artificial tears that I would recommend for my patients to treat their dry eye disease.
The second group of active ingredients is called demulcent.
This is the main ingredient in artificial tears which determines the consistency and thickness of
the drop. Demulcents are typically mucoprotective agents. They reduce inflammation and irritation
of the mucous membrane of the eyes, and hold moisture to lubricate the surface of the eye.
They act on both the aqueous and the mucin layers of the tear film. There are a few
common demulcents used by different brands of artificial tears. Carboxymethyl cellulose sodium
(CMC) is the main demulcent used in refresh brand artificial tears made by Allergan.
systane brand of artificial tears made by Alcon typically contain polyethylene glycol
or propylene glycol as their demulcent. The other commonly used demulcent agent is hydroxypropyl
methylcellulose (HPMC), it is the demulcent used in GenTeal brand artificial tears made by Alcon.
Variation in the concentration of the demulcent such as CMC affects the consistency and the
viscosity of the artificial tears. For example refresh optive gel drop contains 1.0% CMC, which
is double the concentration of CMC in the regular refresh optive eyedrop. This allows the gel drop
to provide a longer lasting lubricating effect. However the higher concentration of the demulcent
used increases the thickness of the artificial tears. This will require more blinking action
by the eyelid to spread the demulcent polymer over the surface of the eye. Therefore if you
use a gel eyedrop you may notice it takes a little bit longer and more blinks to clear
your vision after you putting in the eyedrop. The third category of the active ingredients
is emollient. An Emollient is usually a fat or oil providing a long-lasting lubricating effect,
and eye drops which contain emollients tend to be thicker and take longer to clear up. so the liquid
formulations of artificial tears typically do not contain a large amount of emollients. For example,
mineral oil is a commonly used emollient and is intended to replace and thicken the lipid layer of
the tear film in order to improve the stability of the tears and slow down evaporation of the tears.
More commonly, emollients are found in ointment formulations of artificial tears,
such as refresh PM and Systane nighttime eye ointments. These formulations are more
frequently used before bedtime and reserved for moderate to severe dry eye disease.
Some newer liquid formulations of artificial tears that target all three layers of the tear film,
including the lipid layer, often contain a small amount of emollient
to provide a longer-lasting lubricating effect to the eye.
artificial tears which contain emollients are a little bit thicker , so after you put in the drop,
make sure you blink a few times to spread out the eyedrop across the surface of the eye. You
may notice the vision is a little bit blurry and it may take a few blinks to clear up your vision.
I have included the links to a few examples of those newer
formulations of artificial tears in the description down below.
Now you have learned about the active ingredients in artificial tears, and the next main category
of ingredients is the inactive ingredients, such as sorbitol and sodium hyaluronate.
sodium hyaluronate is one of the most commonly used inactive ingredients in artificial tears
to provide additional lubrication to the surface of the eye. sodium hyaluronate is a derivative of
hyaluronic acid and it is hypoosmotic, what this means is that it can actually lower the osmolarity
of the tears. It is made naturally by the eye when there's damage to the surface of the eye,
and it helps repair damaged cells on the epithelial layer of the cornea, which
is the outermost layer of the cornea. It also reduces inflammation on the surface of the eye.
Sodium hyaluronate has better osmolarity lowering properties than glycerin.
A few examples of artificial tears that contain sodium hyaluronate are Systane complete made
by Alcon, refresh relieva made by Allergan, and blink artificial tears made by Johnson & Johnson.
Other common inactive ingredients include electrolytes, such as magnesium chloride
and potassium chloride. electrolytes are typically added to the artificial tears
to lower the osmolarity of the tears to prevent it from pulling water away from
the superficial layer of the cornea and drying the surface of the eye.
The last category of artificial tear ingredients I want to spend some time to talk about
is preservatives. All preservatives used in artificial tears are somewhat toxic
to the surface of the eye to varying degrees. Therefore I recommend my patients
to use preservative free artificial tears whenever possible. However the preservative free artificial
tears are typically packaged in single use vials, and they are more costly and inconvenient
when compared to the artificial tears packaged in multidose bottles. Preservatives play an
important role in preventing contamination of eyedrops stored in multidose bottles. Bacteria,
fungus, and other contaminates, can potentially cause infection on the surface of the eye.
Not all preservatives have the same level of toxicity to the surface of the eye;
some are more toxic than others. Let's take a closer look. There are three main types of
preservatives used in artificial tears: detergent type, oxidative type, and ionic buffering systems.
The detergent type of preservative is the most toxic one to the surface of the eye.
One of the most commonly used detergent preservatives is BAK short for benzalkonium
chloride. It is a common preservative used in many different types of medication eyedrops,
such as antibiotic eyedrops and glaucoma eyedrops. It kills bacteria by destroying
the lipids on the cell membrane of the bacteria. Some examples of artificial tears containing BAK
are Visine dry eye relief and clear eyes redness relief as well as sooth long lasting artificial
tears by Bausch & Lomb. Polyquad is another commonly used detergent type of preservative that
is derived from BAK. It is unique because it can attract bacteria cells but the epithelial cells on
the surface of Cornea tend to repel it. Therefore it’s better tolerated and less toxic than BAK.
Polyquad is the preservative used in the Systane family of artificial tears . The oxidative
preservatives are less toxic to the surface of the eye than the detergent preservatives.
purite is the brand name of a Stabilized oxychloro complex preservative used in the refresh family
of artificial tears. It Is an oxidative type of preservative, when exposed to the light,
it degrades into water, oxygen, sodium, and chlorine free radicals. It kills bacteria
by interfering with bacterial protein synthesis. There are other types of oxidative preservatives
in other brands of artificial tears. For example, sodium perborate, also known as GENaqua used in
GenTeal brand artificial tears, and Dequest used in thera tears Brand artificial tears.
ocupure is another type of oxidative preservative that is similar to purite
and it is used in blink brand artificial tears. Now you have learned all about artificial tear
ingredients, please check my video on my top five picks of artificial tears.
Thank you for watching and I hope you find this video helpful in learning more about the science
behind the ingredients of artificial tears. So the next time when you go to a pharmacy to pick
a bottle of artificial tears, you will know the differences between them and you can pick
the one that works the best for you. let me know which over-the-counter
artificial tears and dry eye drops are your favorites in the comments below.
If you find this video helpful please don't forget to like, share this video,
and subscribe to my channel to help me bring you more videos about eye health and eye surgery.
To learn more about my practice you can follow me on Facebook and LinkedIn @DRAudreyTai.
Thank you again for watching and I will see you in the next video.