Understanding Open Angle Glaucoma
Summary
TLDRThis video by Zero to Finals covers open-angle glaucoma, a condition caused by increased intraocular pressure leading to optic nerve damage. The presenter explains the anatomy and physiology of the eye, focusing on the flow of aqueous humor and its role in maintaining eye pressure. The video discusses the causes, symptoms, and diagnosis of open-angle glaucoma, highlighting risk factors like age, family history, and myopia. Treatments include eye drops, beta blockers, and surgical procedures, aiming to reduce pressure and prevent further vision loss.
Takeaways
- đ Glaucoma refers to optic nerve damage caused by increased intraocular pressure.
- đïž Open-angle glaucoma involves a gradual increase in resistance through the trabecular meshwork, causing a slow rise in eye pressure.
- đĄ The aqueous humor flows from the ciliary body through the anterior chamber and drains via the trabecular meshwork into the canal of Schlemm.
- đ Normal intraocular pressure ranges from 10 to 21 mmHg, and higher pressures indicate increased resistance to aqueous humor flow.
- đ Risk factors for open-angle glaucoma include age, family history, black ethnic origin, and nearsightedness (myopia).
- đïžâđšïž Open-angle glaucoma often presents without symptoms but can lead to gradual peripheral vision loss, tunnel vision, and night-time halos around lights.
- đ©ș Two common methods to measure intraocular pressure include non-contact tonometry (air puff test) and Goldman applanation tonometry (more accurate).
- đŹ Diagnosis of glaucoma involves checking intraocular pressure, optic disc cupping, and visual field assessment for peripheral vision loss.
- đ§ First-line treatment involves prostaglandin analogs like latanoprost, which increase the outflow of aqueous humor and reduce pressure.
- đ§ Surgery, such as trabeculectomy, may be needed when eye drops are ineffective, creating a new drainage channel for aqueous humor.
Q & A
What is glaucoma, and how is it related to intraocular pressure?
-Glaucoma refers to optic nerve damage caused by a significant rise in intraocular pressure (IOP). Elevated IOP occurs due to a blockage in the drainage of aqueous humor from the eye, leading to increased pressure.
What are the two main types of glaucoma, and which type is discussed in the video?
-The two main types of glaucoma are open-angle and closed-angle glaucoma. The video focuses on open-angle glaucoma, where the resistance to the outflow of aqueous humor through the trabecular meshwork increases gradually.
How does aqueous humor flow through the eye, and how is it related to intraocular pressure?
-Aqueous humor is produced by the ciliary body, flows from the posterior chamber to the anterior chamber, and drains through the trabecular meshwork into the canal of Schlemm. Resistance to this outflow creates intraocular pressure; if the resistance increases, the IOP rises.
What is the normal range of intraocular pressure, and what happens when this pressure increases in open-angle glaucoma?
-The normal intraocular pressure is between 10 to 21 mmHg. In open-angle glaucoma, increased resistance in the trabecular meshwork leads to a gradual rise in pressure, causing damage to the optic nerve over time.
What is optic disc cupping, and how is it associated with glaucoma?
-Optic disc cupping occurs when raised intraocular pressure causes the optic cup (a small indent in the optic disc) to become larger and deeper. An optic cup greater than 0.5 the size of the optic disc is considered abnormal and may indicate glaucoma.
What are the key risk factors for developing open-angle glaucoma?
-Risk factors for open-angle glaucoma include increasing age, family history of glaucoma, black ethnic origin, and myopia (nearsightedness).
How does open-angle glaucoma typically present, and what are the common symptoms?
-Open-angle glaucoma often presents asymptomatically, with a gradual loss of peripheral vision (tunnel vision), fluctuating pain, headaches, blurred vision, and halos around lights, especially at night.
What are the methods used to measure intraocular pressure, and how do they work?
-Intraocular pressure is measured using non-contact tonometry, which estimates IOP by shooting a puff of air at the cornea, and Goldmann applanation tonometry, the gold standard, which applies pressure to the cornea to get an accurate measurement.
How is open-angle glaucoma diagnosed?
-Diagnosis involves measuring intraocular pressure with Goldmann applanation tonometry, assessing optic disc cupping through fundoscopy, and checking for peripheral vision loss using visual field tests.
What are the treatment options for managing open-angle glaucoma?
-Treatment aims to reduce intraocular pressure. First-line treatment includes prostaglandin analogs like latanoprost, which increase uveoscleral outflow. Other options include beta blockers, carbonic anhydrase inhibitors, sympathomimetics, and surgical procedures like trabeculectomy if eye drops are ineffective.
Outlines
đïž Introduction to Open-Angle Glaucoma
Tom from Zero2Finals introduces open-angle glaucoma, explaining that it's caused by damage to the optic nerve due to a rise in intraocular pressure. The blockage of aqueous humor within the eye increases pressure, leading to glaucoma. He briefly outlines the types of glaucomaâopen and closed angleâbefore diving into the basic anatomy and physiology of the eye, focusing on the aqueous humor's production and flow. The trabecular meshwork, the resistance it creates, and its role in regulating intraocular pressure are also explained.
đ§ Pathophysiology and Effects of Open-Angle Glaucoma
Tom explains that open-angle glaucoma develops gradually due to increased resistance in the trabecular meshwork, resulting in a slow buildup of intraocular pressure. This chronic pressure leads to cupping of the optic disc, where the optic cup expands due to pressure, indicating glaucoma if it exceeds half the size of the optic disc. Risk factors include age, family history, black ethnic origin, and myopia. He notes that early stages of the disease are often asymptomatic and detected during routine eye exams, with peripheral vision being affected first.
đ Symptoms and Diagnosis of Open-Angle Glaucoma
Tom describes the symptoms of open-angle glaucoma, which include gradual peripheral vision loss, tunnel vision, fluctuating pain, headaches, and halos around lights, especially at night. He explains two methods to measure intraocular pressure: non-contact tonometry (using a puff of air) and Goldman applanation tonometry (the gold standard). These methods help diagnose glaucoma, alongside fundoscopy (to check for optic disc cupping) and visual field assessments (to detect peripheral vision loss).
đ Treatment and Management of Open-Angle Glaucoma
The goal of glaucoma treatment is to reduce intraocular pressure, especially when it reaches 24 mmHg or above. Prostaglandin analogs like latanoprost, which increase uveoscleral outflow, are the first-line treatment, though side effects include eyelash growth and iris pigmentation. Other treatments include topical beta blockers, carbonic anhydrase inhibitors, and sympathomimetics, all aiming to reduce aqueous humor production or increase its drainage. In severe cases, a trabeculectomy surgery may be performed to create a new drainage channel for the aqueous humor.
đą Conclusion and Resources
Tom concludes the video by encouraging viewers to explore more resources on Zero2Finals.com, including detailed notes, illustrations, questions, books, and flashcards. He also mentions his personal YouTube channel where he shares tips on learning medicine. He encourages viewers to subscribe and follow the channel for more content.
Mindmap
Keywords
đĄOpen-angle glaucoma
đĄIntraocular pressure
đĄAqueous humor
đĄTrabecular meshwork
đĄOptic nerve
đĄCupping of the optic disc
đĄNon-contact tonometry
đĄGoldman applanation tonometry
đĄProstaglandin analogs
đĄTrabeculectomy
Highlights
Introduction to open-angle glaucoma, explaining it as optic nerve damage caused by a rise in intraocular pressure.
Open-angle glaucoma is due to increased resistance in the trabecular meshwork, leading to slow pressure buildup in the eye.
The anatomy of the eye, including the roles of the anterior and posterior chambers, filled with aqueous humor, is essential to understanding glaucoma.
Aqueous humor is produced by the ciliary body and drains through the trabecular meshwork into the canal of Schlemm.
Intraocular pressure normally ranges between 10 to 21 mmHg, with higher pressure indicating potential glaucoma.
Cupping of the optic disc is a key sign of glaucoma, where the optic cup becomes larger due to increased pressure.
Risk factors for open-angle glaucoma include age, family history, Black ethnic origin, and myopia (nearsightedness).
Open-angle glaucoma is often asymptomatic in early stages, detected during routine eye exams by checking intraocular pressure.
Peripheral vision is affected first in glaucoma, leading to tunnel vision as the disease progresses.
Glaucoma can also present with symptoms like fluctuating pain, headaches, blurred vision, and halos around lights, especially at night.
Non-contact tonometry is a common, less accurate way to measure intraocular pressure by using a puff of air.
Goldman applanation tonometry is the gold standard for measuring intraocular pressure, involving direct contact with the cornea.
Management of glaucoma aims to reduce intraocular pressure, with treatment often starting at 24 mmHg or above.
Prostaglandin analogues like latanoprost are first-line treatments, increasing the uveoscleral outflow to reduce eye pressure.
Surgical options, such as trabeculectomy, create a new drainage channel for aqueous humor when eye drops are ineffective.
Transcripts
[Applause]
[Music]
hi this is tom from zero2finals.com
in this video i'm going to be going
through open angle glaucoma
and you can find written notes on this
topic at zero to finals dot com slash
open angle glaucoma or in the
ophthalmology section
of the zero to finals medicine book
so let's jump straight in glaucoma
refers to the
optic nerve damage that's caused by a
significant rise in
intraocular pressure the intraocular
pressure is essentially the pressure
within the eye
itself raised intraocular pressure is
caused by a blockage
in the aqueous humor trying to escape
the eye
and we'll talk more about the
pathophysiology shortly
there are two types of glaucoma open
angle
and closed angle and here we're going to
be talking about
open angle so let's talk about the basic
anatomy and physiology because it's
important to understand
some basic anatomy and physiology of the
eye and how the eye
functions in order to understand the
pathophysiology
of glaucoma the vitreous
chamber of the eye is filled with
vitreous humor
and this is the main bulk the main area
of the eye
the anterior chamber is between the
cornea and the iris
and the posterior chamber is between the
lens and the iris
these anterior and posterior chamber are
filled with
aqueous humor that supplies nutrients to
the cornea and keeps it healthy
the aqueous humor is produced by the
ciliary body
and then the aqueous humor flows around
the iris
from the posterior chamber into the
anterior chamber
where it drains through something called
the trabecular
meshwork at the angle between the cornea
and the iris
the aqueous humor flows from the ciliary
body
around the lens and under the iris
through the anterior chamber through the
trabecular meshwork and
into something called the canal of
schlem
from the canal of slam it eventually
enters the general circulation
and is reabsorbed into the body the
normal
intraocular pressure is 10 to 21
millimeters of mercury and this pressure
is created by the resistance to flow
through the trabecular meshwork so
aqueous humor
is trying to flow through the trabecular
meshwork
out of the eye and if there's more
resistance in the trabecular meshwork
the pressure will go up because there's
more resistance
of aqueous humor trying to escape the
eye if there's less resistance
the pressure will go down because the
aqueous humor is able to flow more
freely out of the eye
so let's talk about the pathophysiology
of open-angle glaucoma
and in open-angle glaucoma there's a
gradual
increase in resistance through the
trabecular meshwork
and this makes it more difficult for
aqueous humor to flow through the
meshwork and
exit the eye therefore the pressure
slowly builds within the eye
and this gives a slow and chronic onset
of glaucoma so let's talk about the
effects of the increased pressure in the
eye
and this causes cupping of the optic
disc
and remember in the center of a normal
optic disc is something called the optic
cup and this is a small indent in the
optic disc
and is usually less than half the size
of the optic cup
and when there's a raised intraocular
pressure this
indent becomes larger because the
pressure in the eye puts pressure on
that indent making it
wider and deeper this is called cupping
an optic cup greater than 0.5 the size
of the optic disc
is abnormal so if the optic cup is more
than half the size
of the optic disc this suggests
cupping and could indicate glaucoma
so what are the risk factors for open
angle glaucoma or increasing
age family history black ethnic origin
and near-sightedness which is called
myopia are all
key risk factors to remember for your
exams
let's talk about the presentation of
open angle glaucoma
often the rise in intraocular pressure
is asymptomatic for a long period of
time
it's usually diagnosed by routine
screening when they attend an
optometry appointment for an eye check
so whenever you get your eyes checked at
the optometrist
they check the intraocular pressure to
see whether there's any possibility
you've developed glaucoma
glaucoma tends to affect the peripheral
vision first
so there may be a gradual loss of
peripheral vision
as it closes in slowly and they
experience something called tunnel
vision
it can also present with gradual onset
of fluctuating pain
headaches blurred vision and typically
halos surrounding lights which are worse
at night time
so if a patient is losing their
peripheral vision and at night time they
see halos appearing around lights
think about glaucoma
so how can we measure intraocular
pressure well there's two
main ways we can measure the intraocular
pressure the first is something called
non-contact
tonometry and this is commonly used with
a machine
to estimate the intraocular pressure
when you go to an opticians
and this involves shooting a puff of air
at the cornea
and measuring the corneal response to
that puff of air
if the cornea has a lot of pressure
inside it from glaucoma
it won't react very much when air is
shot at it
whereas if you've got a very soft cornea
with a lack of
intraocular pressure there'll be a large
reaction to that puff of air
this is a less accurate way of measuring
the intraocular pressure
but it gives a helpful estimate for
general screening purposes
the second way of measuring intraocular
pressure is something called
goldman applination tonometry
this is the gold standard way of
measuring the intraocular pressure
this involves using a special device
mounted on a slip lamp
that actually makes contact with the
cornea and applies different pressures
to the front of the cornea to get an
accurate measurement of the intraocular
pressure
so the machine actually presses down on
the cornea
to check how much resistance there is
and indicate how much pressure there is
within that cornea
so how do we make a diagnosis of
glaucoma well firstly
using a goldman applination tonometry
which can be used to check the
intraocular pressure
fundoscopy is used to assess
the optic disc for cupping and also for
optic nerve health
visual field assessment is important to
check for peripheral vision loss
and all three of these will be useful
for making the diagnosis
so how do we manage open angle glaucoma
management of glaucoma aims to reduce
the intraocular pressure
treatment is usually started at an
intraocular pressure
of 24 millimeters of mercury or above
patients should be closely followed up
to assess the response to treatment
and treatment will be guided by an
ophthalmologist
the first line treatment is something
called prostaglandin analogues
used as eye drops and an example of this
is
latanoprost and these eye drops increase
the uveo
scleral outflow and the uv scleral
outflow refers to the drainage of the
aqueous humor from the anterior chamber
into the anterior chamber angle
rather than going through the
traditional trabecular meshwork
notable side effects from prostaglandin
analog eye drops like litanoprost
are eyelash growth eyelid pigmentation
and iris pigmentation typically you get
a browning of the iris
the other options for treating open
angle glaucoma are
topical beta blockers like timolol
which reduce the production of the
aqueous humor
carbonic anhydrase inhibitors like
dorsolamide
which reduce the production of the
aqueous humor and
sympanometics such as brimonidine
which reduce the production of aqueous
fluid and also
increase the uv scleral outflow
finally a surgical procedure called
trabeculectomy may be used
where the eye drops are ineffective this
involves creating a new
channel from the anterior chamber
through the sclera
to a location under the conjunctiva this
causes a little bleb
under the conjunctival where the aqueous
humor drains
and the aqueous humor is then reabsorbed
from this bleb into the general
circulation
so it essentially creates a new way for
aqueous humor to drain away from the eye
thank you for watching this video if you
liked the video
left a comment or subscribe to the
channel thank you so much it really
helps
zero to finals is not just a youtube
channel there's also a website with
detailed notes
illustrations and questions an instagram
account where new questions are posted
every day to help you test your
knowledge
books flash cards and much more
i also have a personal channel where i
share my thoughts and tips on learning
medicine
and you can find links to everything in
the description of this video
see you next time
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