NARRATOR: Imagine this. (traffic blares in the background)
You're driving late at night one day, and notice that the lights are blurrier than usual.
The lines on the pavement seem to be blurring into one, and you keep missing your exit.
The following days, you notice that you've lost your peripheral vision,
and cannot see as well as before. (coworkers talking in the background)
So as any responsible adult would, you call the optometrist
and book the soonest appointment for an eye examination.
At the optometrist, you begin to panic as you realize the extent to which your vision has worsened.
You can barely read the examination poster.
The optometrist diagnoses you with early glaucoma.
Getting diagnosed with glaucoma is scary enough as it is.
Looking through treatment procedures is even worse.
Our vision is crucial to our livelihood,
and it is essential that we have annual checkups to detect and correct vision problems
before it is too late.
Before we delve into our topic,
Let's take a look into vision and the anatomy of the eye as a whole.
Here we have a 3D diagram of the anatomical features of the eye.
Let's discuss relevant segments of the eye.
Firstly, we have the cornea:
a transparent segment of the eye that covers the iris and the pupil
and allows light to enter the eye.
It is important to recognize that the cornea is protected by the corneal epithelium:
composed of epithelial tissue which acts as a barrier to the external environment of the eye.
Then, we have the iris:
the coloured segment of the eye which controls the amount of light that enters.
And the pupil – the round structure in the middle of the iris –
changes in size to allow different amounts of light into the eye.
The optic nerve is found at the back of each eye,
connecting the eye to the brain.
Its primary function is to carry visual input to the brain.
This includes brightness perception, colour perception, and contrast.
It is important to note that the fluid that fills the eye
is called the aqueous humour.
Another important aspect of the eye to consider is the anterior region.
It is the front part of the eye between the cornea and the iris, and includes the lens.
Then we have the trabecular meshwork, which is part of the drainage system of the eye.
This is located between the cornea and the iris.
The drainage occurs at the intersection of the iris and the sclera,
which is the white exterior coat of the eye.
The limbus is the border that separates the cornea and the sclera.
It facilitates an environment for aqueous humour discharge,
and is the surgical incision site for glaucoma treatment.
Of course, there are many structures in the eye, but we will be focusing on these for now.
So, what is glaucoma?
Glaucoma is a collection of eye disorders that harm the optic nerve.
For clear vision, the optic nerve – which transmits visual data from the eye to the brain – is essential.
High pressure in your eye is frequently associated with damage to the eye's optic nerve.
However, glaucoma can develop with normal eye pressure as well.
Even while it can take anyone, older persons are more likely to develop glaucoma.
For those over 60, it is one of the main causes of blindness.
Numerous glaucoma types show no symptoms at all.
You might not notice a change in vision until the problem is advanced, since the effect is so gradual.
Usually fluid, otherwise known as the aqueous humour, in the eye
flows freely through the anterior chamber and exits through the drainage system,
also known as the trabecular meshwork.
The pressure inside the eye – the intraocular pressure – develops if that system is obstructed
or not working properly, which in turn destroys the optic nerve.
The most prevalent type of glaucoma causes gradual vision loss,
as demonstrated here by the various glaucoma stages.
Glaucoma can be diagnosed in a variety of ways.
A few of these include tonometry, which is used to measure intraocular pressure,
imaging studies and dilated eye examinations, which typically check for optic nerve damage,
visual field testing, which is the process of looking for spaces where vision is being lost,
gonioscopy, the examination of the drainage angle within the eyes,
and finally, glaucoma can be diagnosed via pachymetry: a test used to gauge corneal thickness.
So, what do typical treatments look like for glaucoma?
Typical treatment options include eye drops, which aim to decrease eye pressure
by redirecting how fluid drains from the eye or by decreasing the eye's fluid production.
The other commonly used treatment options entail invasive procedures,
such as filtering surgery, which involves an incision made in the sclera,
to allow for additional exit for excess fluid in the eye.
Then, there is laser therapy, which aims to ameliorate the drainage of fluid
of the tissue of the junction of the cornea and the iris,
And finally, we have drainage tubes:
another option which aims to decrease pressure through excess fluid drainage.
In this procedure, the physician inserts a small tube in the eye.
Now, you may be asking to yourself, "Are there non-invasive treatments for ocular disease?"
Well, although there is a plethora of coping strategies and pain mediation,
There are not many non-invasive treatment options for glaucoma.
As such, researchers are focusing around stem cell research
to find different treatment methods for certain ocular diseases.
What are stem cells?
So, in short, the body's building blocks are stem cells.
These are cells that give rise to all other cells with specific roles.
Daughter cells are created when stem cells divide properly in the body, or in a lab,
to create more cells.
These daughter cells either differentiate into additional stem cells,
or cells with a more specialized purpose.
"Now, what are limbal stem cells?" You may ask.
Well, limbal stem cells are the adult stem cells found within the basal epithelial layer
of the corneal limbus of the eye.
They are particularly of importance, as they promote the reproduction of the corneal epithelium.
which is an essential component in protecting the outer layer of the eye from our environment.
Stem cell research is particularly important for non-invasive treatment options research,
especially regenerative medicine.
Regenerative medicine aims to repair or replace damaged cells or tissues.
Through the use of corneal limbal stem cells from a donor or the patient's other eye,
It can help find a more non-invasive option for glaucoma patients.
Through research, it has been found that it is very successful in animal models,
yet it has yet to be used in humans.
There is a huge need for regenerative medicine.
Reviewing the scientific paper,
"Delivery of Cells to the Cornea using Synthetic Biomaterials,"
will be discussed within the next few minutes.
Regenerative medicine is a valuable tool for tissue repair and regeneration,
and it is typically less invasive that most procedures.
This may provide several possibilities for future research on disease mechanisms as well.
Now if you don't take my word for it,
here is Dr. Aftab Taiyab providing his expertise regarding the matter.
Dr. Aftab Taiyab is in the Department of Pathology and Molecular Medicine at McMaster University,
and his research focuses on developing novel treatment methodologies for glaucoma,
investigating genes and their relation to the development of glaucoma in animals,
and its correlation to glaucoma in humans.
TAIYAB: So with respect to glaucoma, the risk factor currently is the intraocular pressure,
created by the aqueous humour.
This leads to pressure induced cell death, and that basically results in glaucoma.
By decreasing the intraocular pressure, that is the only current treatment that is accepted.
The other methodology is not exactly regenerative medicine or stem cell therapy:
It is more of cell reprogramming done by transfer of certain genes to the posterior end to regenerate.
Currently, those methodologies are not in practice because they are not found to be safe in humans.
But this method is effective and safe in mouse and rabbit models.
But stem cell therapy is kind of far-fetched at this moment, with respect to glaucoma.
Now with the cornea, it is possible and it has been shown to be very effective.
So there is a difference between regenerative medicine
in the anterior segment versus the posterior segment of the eye.
TAIYAB: The biggest myth was that the stem cells are only derived from human embryos.
That is not true. Embryonic stem cells are also there,
but they are not being employed currently for treating diseases in humans due to regulation.
To be honest, it's unethical as well.
However, the scientists have come up with reprogramming of adult stem cells.
Currently there are methodologies where the stem cell of one’s body is extracted,
and they are injected back into the same human.
TAIYAB: So we have been trying to understand the role of activating protein 2 beta
in the development of trabecular meshwork, and how absence of AP2 beta leads to glaucoma.
What we do is that we basically delete AP2 beta in the developing neural crest cells in mice.
Basically, the gene is deleted when the neural crest cells starts migrating to the eye.
Neural crest cells are specialized cells that contribute to the formation of several organs,
including: skull, eye, cardiac stem cells, heart…
In the eye, it basically contributes to the development of trabecular meshwork.
We have shown recently that AP2 beta is involved in the development of trabecular meshwork
and that deletion of AP2 beta leads to glaucoma in mice.
TAIYAB: Look at your eye, you see your iris, which is the colourful...
it can be blue or black or brown, whatever color. And you see the white part, which is the sclera.
And the limbal region basically is just at the border of that black area and the white area.
It's just the border. In this area, limbal stem cells reside.
and their work is to regenerate and maintain the corneal epithelial cells.
TAIYAB: So with the corneal transplant,
it is just the central cornea that is transplanted and not the limbal region.
And that makes it really difficult. And there is a scientist, Virender Sangwan.
So what he did, he took the limbal stem cells and then glued to the area of the person
who was suffering from limbal stem cell deficiency.
The limbal stem cells went automatically to where they belonged
and started residing there and protected the patients.
TAIYAB: In the developing trabecular meshwork, it is basically cell death.
Somehow AP2 beta is kind of contributing to trabecular meshwork cell proliferation.
TAIYAB: In the developing trabecular meshwork, it is basically cell death.
Somehow AP2 beta is kind of contributing to trabecular meshwork cell proliferation.
TAIYAB: The first thing is that we cannot delete a gene in humans.
It’s just the mouse that we study and try to see if the gene is kind of involved.
So our main goal doesn't stop here, of course we have shown the role of AP2 Beta.
What can we do to this mice to relieve the intraocular pressure without surgical intervention?
It’s a very tough and difficult surgery, and it is very invasive.
Because even after surgery, since the trabecular meshwork is completely absent,
the iris will join the cornea after some time. They may have to go multiple surgeries.
So there has been a lot of drugs out there.
There are other methodologies, where they kind of do the surgery of trabecular meshwork
and try to release the pressure there.
Another recent drug has come out, they insert into the aqueous chamber
and that slowly keeps on releasing the drug and that brings down the intraocular pressure.
This mouse model can be used to test new drugs.
So we are trying to use this model system to understand and find a way to kind of treat those patients.
NARRATOR: Because our vision is such a crucial part of our livelihood,
I hope this video helped inform you of the possibilities of glaucoma,
and the importance of getting regular eye checkups and examinations from your physicians.