so having dry eyes is a lot more complicated than just having the occasional dry eye
symptoms you may know this as the redness gritty or burning sensations on the eyes
but having dry eye syndrome where your eye becomes chronically or severely dry
that's when the eye can become painful and even cause your vision to be blurry so in this video
i'm going to break down what causes dry eyes because there's a lot of confusion out there
and i want to help you understand what dry eye is and ultimately how you and your doctor can
work together to help cure your dry eyes that's today's video let's take a look
hello and welcome this is Dr. Allen here from the Doctor Eye Health show helping
you learn all about the eyes and vision on this channel we do a lot of educational videos just
like this one all about eye care topics and if you're interested in learning more about
the eyes your vision and seeing your best then consider hitting the subscribe button down below
so that you don't miss any of our future videos in addition this video is part of a complete
dry eye series all in an effort to help you better understand what's going on with dry
eyes ultimately the causes of dry eyes and their different treatments so if you want to learn more
about dry eyes the treatments that are available both ones over the counter and in the office
through your medical provider then definitely check out the whole youtube playlist below i'll
include a link to that in the top of the video description so you can check it out easily so
when it comes to understanding exactly what causes dry eyes the first thing that we want to review is
the contents of the tear film the easiest way to think of the tear film is in three layers there's
the lipid layer which helps protect your tears from evaporating there's the liquid component
of the tear is called the aqueous layer of the tear that's mostly water and then you have the
mucous layer of the tear film which kind of binds the aqueous or liquid component of the tears to
the surface of the eye now the aqueous component i also want to mention also contains electrolytes or
salt and then it also contains proteins and that's important because as the salt content changes
of the liquid tear film then that can contribute to a major component of dry eye disease and we're
going to touch on that in just a moment now eye care thinks and categorizes dry eye disease into
three main categories the first category is called aqueous deficient dry eye that's where you don't
produce enough of the liquid aqueous component of your tear film then you have an evaporative
form of dry eye where the tear film evaporates too quickly you may still produce enough liquid
but the tears themselves are evaporating faster than you can produce it and then there is a mixed
form right in the middle that's somewhere on the timeline between aqueous and evaporation but
most people studies show that about 90 percent of most people who have dry eye disease have
some form of the mixed form of dry eye now when it comes to the aqueous deficient dry eye let's cover
some of the main causes for aqueous deficiency one of the first ones is hormone changes we know
that a lot of people suffer from dry eyes later in lifetime people can still have it when they're
younger but usually people have it as they get into their 50s and above a lot of women tend
to have dry eyes more than men and that has to do with testosterone level changes again as we
age and that's why oftentimes women will get dry eyes about 20 to 25 years *EARLIER before
men do before testosterone starts to change next up is sensory block that's where nerves within
the eye are supposed to pick up sensations of dryness and send that signal to your brain and
then back to your eye and the lacrimal glands to produce more tears unfortunately for people who've
either had trauma or some sort of infection like a virus or potentially other refractive procedures
such as LASIK these different receptors these nerves can be severed and they don't function
the same way in fact they don't even grow back properly and so you're not getting that feedback
mechanism to your brain to produce more tears that is why a lot of people having LASIK eye surgery
can end up with really severe forms of dry eye another major cause of aqueous deficiency has to
do with medications if you're somebody who takes a lot of systemic medications for different diseases
these medications oftentimes do dry out the body most notably are going to be antihistamines such
as oral antihistamines you take for allergies as well as any medications for high blood pressure
these medications are most famous for drying out the body usually you have to urinate more often
and so you end up with just not having enough liquid in your body to help produce tears so
it's important to remember to drink lots of water next up for the aqueous deficient forms of dry
eye is that of autoimmune and inflammatory causes one of the most famous autoimmune conditions that
cause this form of dry eye is one called sjogren's syndrome i have gone over that more in depth in
another video but in short sjogren's syndrome is an autoimmune condition that attacks your parroted
glands your saliva secreting glands here in your cheeks but it also attacks your lacrimal gland
and prevents it from making mucus the other component are inflammatory causes this can be
things like arthritis such as rheumatoid arthritis and this can cause an inflammatory cascade
that essentially turns off your lacrimal gland and you don't produce as much tears this of course is
not the complete list of everything that causes aqueous deficiency but these are by far the most
common culprits for this condition now let's go on to evaporative forms of dry eye because this
is honestly one of the parts that i find most interesting because this is the type of dry eye
i have and this is really concerning for a lot of eye care professionals because this is not just
causing issues later in life for older individuals like aqueous deficiency but in fact evaporative
forms of dry eye are starting to show up in younger individuals even people in their younger
teen years now when it comes to the evaporative forms of dry eye there is an environmental
component and we're talking about the humidity temperature and airflow when there's a really low
humidity especially here in the winter time in Minnesota where i live in practice the furnaces
are on and that usually causes the humidity to be very low and that tear film is going to evaporate
quicker into the air temperature in general if it's hotter outside or indoors it's going to again
cause your tear film to evaporate faster and then airflow so if you have air conditioning a fan or
maybe you're outside winds blowing against your eye your tear film is again going to evaporate
quicker and then you're going to end up with more dryness now this next one is really important to
listen to because this affects so many people even younger individuals who are on things
like the computer all day and that is poor blink rate and poor eyelid closure when we're sitting
just in conversation we typically blink around 20 times a minute but as soon as we go on to a near
device we're looking at your phone a computer screen a tablet then your blink rate drops to
only about five times per minute and that can be significant because then your eyes are going to be
open and your tear film is going to be evaporating much faster in addition to just a poor blink rate
oftentimes people don't close their eyes completely like myself i only complete kind
of half blink i blink enough for my eyelid comes just below my pupil here so my brain thinks that
i've closed my eyes but in fact i've left about one third to one half of my entire eyelid open and
that's always exposed to air so the tear film is constantly evaporating very quickly and i need to
remind myself to close my eyes all the way when i blink some people even have eyelid closure issues
while they're sleeping which we call lagophthalmos and that means their eyes are open all night long
and their eyes are just drying out very quickly and you may have that experience where you wake up
in the morning and your eyes are very gritty and sandy and almost feel like they are stuck together
to the eye when you first open your eyelids now what's even more important about understanding how
poor blink rate plays a role in dry eyes is the effect on your oil glands within the eye now the
oil glands called the Meibomian glands they live in your eyelids and every time you blink these oil
glands secrete a little bit of oil remember that lipid layer on the tear film that we discussed
earlier that tear lipid layer is going to protect those tears from evaporating now if you're not
blinking enough that means these oil glands which are activated by the full blink on the eye then
you're not getting enough oil secreted to even protect the tears from evaporating furthermore if
you're not blinking enough and you're not blinking completely if you're not completely blinking like
i don't then these oils can get trapped in the oil glands and they can sit there they can solidify
into more of a wax instead of an oil and then they can even go rancid causing inflammation
of the eyelids and we call that Meibomian gland dysfunction or MGD and that is a huge component
of dry eye disease in fact about 80 some percent of all dry eye sufferers have mgd to some extent
and if you ever continue through more of our video series on dry eye you'll notice a lot of focus on
mgd treatments and then finally contact lens wear can play a role in dry eye syndrome namely because
it does increase the evaporative component of dry eye because the tear film kind of spreads unevenly
on top of those contacts it can cause sensory changes or adaption to the surface of the eye so
your brain isn't getting the same sensory feedback loop you can also have a poor blink rate and then
the contact lenses themselves can not only soak up tears on the surface of the eye but if they're
not fitting properly they can damage surface cells on the front surface of the eye named goblet cells
and so that can all be contributing factors for this forms of dry eye disease now next up we're
going to touch on the inflammatory cycle of dry eye and why the inflammatory cycle makes dry eye
syndrome so difficult to treat but first let us know how you're liking this video by smashing the
like button and then dropping a comment down below about what type of dry eye you think you have do
you have aqueous deficient evaporative forms or a mix of the two let us know your story so we
can all learn from each other now the reason dry eye syndrome can become so severe and chronic for
people is that the inflammatory cycle will kick in and that's where aqueous deficient evaporative
mix forms a dry eye they start to change the salt content of your tear film do you remember back the
beginning of the video i mentioned how the tear film also has salt and proteins in it well what
happens if imagine that your evaporation of your tear film the tear film is evaporating well you're
losing the liquid portion of your tears but the salt content of the tears stay behind so if the
salt content stays behind it's going higher and higher in salt and we call that having a hyper
osmolarity that means the equilibrium of the surface of the eye has shifted away from normal
and that can cause damage to cell membranes on the surface of the eye in fact in the eye clinic
we see these as little spots that we call SPK superficial punctate keratopathy and in extreme
cases it even looks like someone took sandpaper and scratched the front surface of the eye
after that every time you blink because the eye is so dry and irritated it's almost like you have
an open wound that you're scratching every time your eyelid is coming up and down and that further
aggravates the eye releasing inflammatory proteins which basically just starts the cycle over again
where the inflammatory proteins can trigger inflammatory causes for aqueous deficiency
they can cause inflammation on the oil glands on the surface of the eyelid which again cause
evaporation and even the inflammatory proteins can contribute to damage of the ocular surface
and that's exactly why in so many of our videos here on this channel we're going to cover
different treatments for dry eye and why so many of those treatments focus on first controlling
the inflammatory cycle along with treating the root causes so hey i hope you enjoyed today's
video if you found it helpful please go ahead and share it with friends family or anyone you
know who's suffering from dry eyes so they can take better control of the dry eye disease if
you want to learn more and check out our full series about dry eye and dry eye treatments go
ahead and click or tap the screen over here over here to the side and you can check that out easily
again this is Dr Allen here from dr eye health keep an eye on it and we'll talk to you soon