Diabetic retinopathy | Endocrine system diseases | NCLEX-RN | Khan Academy
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Diabetic retinopathy | Endocrine system diseases | NCLEX-RN | Khan Academy

September 10, 2019


– Did you know that diabetes
is the most common cause of blindness in individuals
from the ages of 25 to 65? And blindness can be caused by multiple different complications
associated with diabetes including glaucoma and cataracts, however in this tutorial, let’s
discuss the most common cause of blindness due to diabetes which is a condition known
as diabetic retinopathy. And if we break down the term, we can receive generally, an understanding of what this disease is,
so you have retino here meaning the retina, and
pathy meaning disease. So, diabetic retinopathy
is a disease of the retina that’s caused by diabetes. And to describe what the retina is, let’s bring in a diagram of the eye and go through some of the structures as it will help us as we learn
more about this condition. Over here on the left, we have
a cross-section of the eye and there’s a few important
structures to note. So this is the front of the eye here, and this is the back of the eye, and this part right here
is known as the cornea. And it is where light
initially passes through as it goes through the
eye, and then it hits this structure right here,
which is known as the lens. And the lens focuses the
light on this structure in the back of the eye, this
kind of brownish structure, and this is the retina. And then exiting the back of the eye here, this is the optic nerve. Then, you can also see
all of these blood vessels that are traveling through the retina and then exit the back of the eye in the middle of the optic nerve. So if you look over here on the right, this is a front view of the eye. So this is kind of what it looks like when a doctor looks in to your eye. So here, right here we have what’s called the optic disc, and the
optic disc is really just the convergence of the retina and where it exits the
eye, so this is really actually the optic nerve
exiting the back of the eye. And then over here, you have a structure called the fovea. And the fovea is the portion of the retina with the highest density of cones which are the nervous receptors that correspond with color
and more high resolution. So this is the portion of the retina that produces the
highest resolution image. So, in a sense, you can
kind of think of the fovea as producing an HD or a high
definition quality image whereas kind of the more
periphery of the retina on the outside will produce
a much lower quality image. Now that we have a very
basic general orientation to the eye and the retina,
let’s use this drawing to discuss the three stages
of diabetic retinopathy. And they are, diabetes
without retinopathy, non or pre-proliferative
diabetic retinopathy, and proliferative diabetic retinopathy. And one thing that’s important to note is that these stages
of diabetic retinopathy are defined by their pathology. Not by the clinical presentation or their symptoms. But before we dive in
to the pathology here, what are some of the common symptoms of diabetic retinopathy? Well, since it’s a disease of the retina caused by diabetes, it makes
sense that the symptoms are typically visual. And most of the symptoms tend to be fairly mild initially. They are things like blurry vision, or seeing dark spots or floaters. However, sometimes the
symptoms can be very serious. Such as sudden onset of blindness. All right, so now let’s get back to these stages of diabetic retinopathy. So the first stage I’m mentioned is diabetes without retinopathy. So why do we consider
diabetes without retinopathy a stage of diabetic retinopathy? It doesn’t quite make sense. And this is because the stages are dictated by the underlying pathology. And so, long before someone with diabetes develops vision changes,
the underlying hyperglycemia or high blood sugar levels in their blood causes damage to cells known
as pericytes within the retina. So these retinal pericytes are
specialized contractile cells that surround the
retinal vasculature here. And they’re very important
for helping regulate blood flow throughout the retina. And the damage to these pericytes is believed to be caused by an inability to properly metabolize the glucose within these cells. And then this results in osmotic damage. Now this damage to the retinal pericytes is the earliest stage
of diabetic retinopathy and it’s likely present in
many, if not most individuals who have had diabetes
for at least a few years, however, unfortunately this
damage is only detectable under a microscope and
therefore the retina on opthamologic or on an
eye exam looks normal. It looks something like this. So therefore, early in
the course of diabetes individuals will not necessarily
have visual disturbances or signs of disease on exam, however this does not necessarily mean that the damage is not occurring, it’s just not detectable. And the next stage of diabetic retinopathy is that of the non or pre-proliferative diabetic retinopathy. So recall that I just mentioned
that these retinal pericytes help regulate blood
flow through the vessels throughout the retina,
and when they’re damaged this results in the weakening
of the capillary walls, as well as increased blood flow. What happens when these
capillaries are damaged, it allows for the
formation of microaneurysms which are focal dilations
of weakened vessel walls and since these aneurysms occur in the microvasculature of the retina the vessels themselves are very small and not visible on opthamologic exam however, the microaneurysms are. And so they kind of
look like these red dots that just appear kind of randomly throughout the retina. And if we bring in an actual
picture here of the retina you can see that this is actually what they look like under examination. So they’re a little bit harder to see, but they’re these dots right here, right here, and here, which are typically the first clinical sign
of diabetic retinopathy. However, this isn’t the
only clinical finding for this non or pre-proliferative diabetic retinopathy stage. In addition to damaging
the retinal capillaries this loss or damage to
the retinal pericytes also results in increased
vascular permeability. and basically what this means is that the capillaries become leaky. Now this leakiness allows
for large molecules such as proteins and
lipids that are normally retained within the vessels to leak out in to this retinal
tissue, and unfortunately, there isn’t a normal mechanism to allow these to be reabsorbed. So as you can imagine,
if proteins and lipids were to leak out, they get trapped. And this also can be seen
under a dilated eye exam and it kind of appears as these yellow-white flecks on the
retina, as you can see here. And this finding is
known as a hard exudate. And, once again, even though this is just a drawing of the retina, it’s
actually fairly representative of what actual hard exudates look like. So you can see once again
all of these microhemorrhages or microaneurysms in the retina, and then these white-yellow
flecks all over and that’s the proteins and lipids that have leaked out to form these hard exudates in the retina. So these two clinical findings
are very characteristic of this second stage or the
non or pre-proliferative stage of diabetic retinopathy. And because diabetic retinopathy is categorized by the pathologic findings and not necessarily the
clinical presentation, this stage of diabetic retinopathy may or may not be symptomatic, so it usually begins about 15 to 25 years after someone’s initially
diagnosed with diabetes and it can last for many
years before it progresses to the next stage which is proliferative diabetic retinopathy. Now, proliferative diabetic retinopathy can be asymptomatic,
however, it’s pretty uncommon so most individuals that reach this stage of diabetic retinopathy usually will have at least blurry vision or the presence of floaters. And as its name suggests, proliferative diabetic
retinopathy is characterized by vascular proliferation within the retina. And the reason for this is that all of the microvascular
damage that occurs in these first two stages
of diabetic retinopathy results in something called ischemia. And what ischemia is, is
a lack of oxygen supply to the cells of the retina. So, what the retina will do is it tries to compensate for this ischemia by producing a growth factor known as VEGF which stands for vascular
endothelial growth factor. And VEGF does exactly
what its name suggests. It produces new blood vessels. However, these blood vessels in diabetic retinopathy are abnormal, and the retina is not able to compensate for the ischemia. So it looks something like this over time. So you can see there’s all of these new blood vessels that have formed within the retina and similar to the microaneurysms and the hard exudites, this vascular proliferation
can also be identified on a dilated eye exam. And it looks something like this. So you can see some maybe
a little bit more normal, larger vessels in the retina, but then throughout here, are these little bit lighter kind of squiggly looking newer vessels. So this is that vascular proliferation that is indicative of the proliferative diabetic retinopathy. And unfortunately, once
diabetic retinopathy hits this third stage
and becomes proliferative the clinical course is
pretty unpredictable and it can actually be fairly severe, resulting in potentially vision
threatening complications such as vitreous hemorrhage
or retinal detachment. So now that we have a better understanding of the pathological mechanisms of diabetic retinopathy, how
can we use this information to learn how the condition is treated? Well, first off the treatments
are aimed at halting the underlying pathologic mechanisms of diabetic retinopathy, however their use is more commonly dictated
by the severity of symptoms. So we’ll start with the first stage the diabetes without retinopathy, and since the pathologic mechanism of diabetic retinopathy
is directly related to the underlying hyperglycemia associated with diabetes,
the best way to prevent or delay the progression
of diabetic retinopathy is early and aggressive
control of one’s blood sugar with lifestyle modifications
and anti-diabetic medications. However, oftentimes this is not enough, and over time even individuals with very well controlled diabetes may develop diabetic retinopathy. So because these early stages
are often asymptomatic, it’s also important for all
individuals with diabetes to have a yearly dilated eye exam performed by an ophthalmologist to look for the signs
of diabetic retinopathy. Now once an individual has
signs of diabetic retinopathy such as the microhemorrhages
or the microaneurysms and these hard exudites, and they move in to that second stage
of diabetic retinopathy and now the treatment is
dependent on symptoms. So if that individual
is, say, asymptomatic their only treatment is
still to just maintain proper blood glucose regulation and the yearly eye exam. However, as soon as symptoms such as blurry vision or floaters develop, then an individual with
diabetic retinopathy should be placed on anti-VEGF medications. And these medications will prevent the proliferation of new
blood vessels in the retina and therefore help prevent the progression to proliferative diabetic retinopathy. Now, unfortunately once
someone has evidence of proliferative diabetic
retinopathy with this vascular proliferation of the retina, the clinical course is actually
pretty difficult to predict. So for this reason,
anyone in this stage of diabetic retinopathy is
recommended to undergo a procedure known as
laser photocoagulation. And this is a process by which
very precisely focused lasers are used to stop the
growth of these vessels on the retina, and unfortunately this treatment is not necessarily curative it’s more aimed at preventing
serious complications of diabetic retinopathy
such as retinal detachment where, as its name suggests, the retina can become detached from the posterior wall of the eye, or vitreous hemorrhage where
these new blood vessels actually burst and bleed in
to the inside of the eye. And both of these conditions,
may potentially result in permanent blindness, therefore anyone with diabetes who develops sudden onset vision
loss should be evaluated emergently to rule out
these complications. So diabetic retinopathy
is a disease of the retina that’s caused by diabetes
and it tends to be a slow progressive
complication of diabetes that eventually affects
nearly all individuals with diabetes maladies. However, the underlying mechanism of diabetic retinopathy
is directly associated with glycemic control or
blood glucose regulation. Therefore, like many of the
complications of diabetes, proper treatment of the
underlying condition can prevent or at least slow the progression of diabetic retinopathy.

Only registered users can comment.

  1. Thank you ,it is very clear now ,but would please answer my question my mom got the photocogulation treatement but the doctor said she still need to get lentis injection ,she is really afraid of these injection ,would some please answer me..????

  2. some text book may described the 3 stages as Background Retinopathy, PPDR, and PDR, which were little diffient from this clip.

  3. Excellent presentation. But i have one doubt. As you said New vessels are formed in proliferative stage through VEGF. Then how anti VEGF treatment should be started in non (pre) proliferative stage?

  4. why are Anti-VEGF medications not prescribed in the asymptomatic stage of stage 2? Would this not be able to help prevent further progression in the stages?

  5. I enjoyed this presentation. However, the sound was so low that I still couldn't hear it even with my volume at 100%.

  6. I skipped classes the day we talked about this in medschool and the handout was just a bunch of images, no text, no explanations. This video was so useful.

  7. I'm blind for 1 1/2 months four months ago..half of my vision is gone. I did not use medications, just completely cut sugar from my diet..half months later, I'm completely cured..

  8. Thank you. This video is very helpful. The powerpoint presentation and textbook from my school is completely useless.

  9. Nano-grade eye drops should be the last-ditch treatment for diabetic retinopathy.

    @

    All glory belongs to God !

  10. Nano-grade eye drops should be the last-ditch treatment for diabetic retinopathy.

    @

    All glory belongs to God !

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