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  • Glaucoma is one of the leading causes of blindness in the world,

  • and 50% of people who have it don't even know they do.

  • That's because it often has few symptoms

  • and these symptoms can appear after it's too late.

  • So why is this such a stealth disease?

  • There are two main types of Glaucoma:

  • open angle and closed angle.

  • Open angle is the most common and tends to be less severe.

  • It can develop slowly, over time, and go largely undetected unless it's routinely screened for.

  • Closed angle, while less common - can appear suddenly and be quite painful.

  • Both can eventually can lead to vision loss.

  • - My name's John Flanagan, I'm a professor

  • at the School of Optometry at the University of California, Berkeley.

  • I'm also dean of the School of Optometry there.

  • And for the last 40 years I've spent a lot of time researching into the problem of glaucoma.

  • So glaucoma is a neurodegenerative disease,

  • probably the world's most common neurodegenerative disease,

  • but it's really very specific to the eye.

  • To understand Glaucoma, it helps to know the basics of how the eye works.

  • When light reflects an object, it enters your eye, and its first stop is the cornea.

  • Then it's on through the pupil and ultimately the retina where the image is communicated

  • with your brain by way of the optic nerve.

  • It's then interpreted as what you see.

  • And all of this action is aided by the presence of clear fluids and a complex network of nerves.

  • If you just think for a moment about the eye, and we have this layer called the

  • cornea where you would put a contact lens, for example, that's clear.

  • And it has to be clear, otherwise light can't get in and we can't see.

  • Therefore it can't have blood and blood vessels throughout it feeding that tissue.

  • So the way that the eye feeds that tissue is by producing this fluid with all the nutrients;

  • the oxygen and different nutrients bathe the back to help feed it.

  • This all takes place in a network of fibers that surround the wall of the eye

  • and funnel into the optic nerve.

  • When the fluid at the front of the eye stops draining efficiently, pressure increases.

  • This can cause problems with blood flow to the optic nerve, which

  • kills off nerve fibres.

  • The eye, to stay in the correct shape, needs fluid to keep it inflated.

  • We need pressure in the eye because otherwise it would collapse.

  • So it's always this balance between the pressure inside the eye and the pressure in our capillaries.

  • And for most of our lives, that balance is fine.

  • But as we get older, the blood supply may become obstructed, and the fluid drainage not as efficient.

  • This extra fluid increases the pressure on your eye, which in turn damages the cells

  • and fibers that make up your optic nerve which then leads to vision loss.

  • This is glaucoma.

  • The most prone area, the areas that we expect damage first are actually fibers that come

  • in from peripheral vision, the damage happens more with these big fibers as they loop into the top and bottom.

  • So 12 o'clock and 6 o'clock on the optic nerve,

  • they're the ones that seem to be most prone

  • to this damage in glaucoma and die off first,

  • and give us very specific patterns of loss in the eye.

  • You'd think with drainage problems and eye pressure, you would feel it,

  • but that's not always the case.

  • That's what makes the symptoms of Glaucoma so difficult to recognize.

  • If your disease is more advanced, in primary open angle glaucoma you would just start to

  • notice areas of vision missing.

  • Or you know, you miss that person walking on the sidewalk or across the street initially.

  • So they can be quite subtle.

  • You really don't feel pain other than in the much rarer acute angle glaucoma attacks.

  • And it's not that you just feel no pain, your brain is actually overcompensating, adding

  • to the illusion that nothing is wrong.

  • We often have this idea that if somebody is going blind or losing vision that they

  • have sort of dark or gray areas in their vision.

  • And it just doesn't happen like that.

  • Most of the time these sort of diseases, particularly glaucoma, will slowly affect small areas of

  • vision, and affect them unequally in the two eyes.

  • So your brain is very good at merging what we receive, the view of the outside world

  • from each eye, and merges them together to give our percept of the world.

  • Just as an example, if you're looking at a house,

  • and the house has five windows and two doors,

  • if you have glaucoma, your brain would make you see that house

  • just as well as anybody else.

  • But two of the windows might be missing.

  • Your brain would fill in the brick work or the siding

  • and you would just misinterpret

  • the actual scene that you're looking at.

  • So the brain just has this amazing ability to help you feel as though nothing's wrong

  • as you develop these defects.

  • So since there are very few symptoms with Glaucoma,

  • you can't identify it on your own.

  • And your brain is filling in the gaps.

  • So, how do you know if you have it?

  • Routine screenings and knowing your risk factors, such as family history and high eye pressure, are a start.

  • And treatment, if caught early, can include drops, medication, laser and other surgeries.

  • One treatment however, doesn't appear to pass the smell test, just yet.

  • We know that marijuana will actually reduce the pressure in the eye.

  • The problem is, it's very quick and very short-lived.

  • So the therapeutic value of marijuana is a complete failure for glaucoma.

  • You would literally just have to be smoking continuously

  • to have an effect that might be therapeutic.

  • So that's a very long-winded way of saying, don't bother with marijuana with your glaucoma.

  • But there is some hope on the horizon.

  • Especially when it comes to neurological disorders, and Glaucoma is in that category.

  • We're seeing all sorts of really amazing discoveries about neurodegenerative disease and glaucoma.

  • that opens up the potential for new therapeutic

  • treatments that will arrest the damage.

  • I think there's genuine reason for optimism that we'll start having some treatments for

  • neurodegenerative disease as a whole.

  • And specifically for glaucoma.

Glaucoma is one of the leading causes of blindness in the world,

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B2 US eye vision nerve optic angle pressure

How Does Glaucoma Cause Vision Loss?

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    Jerry Liu posted on 2019/10/02
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