Hi, my name is Tom and welcome to this brand new series of the zero to finals podcast on

ophthalmology. And in this episode, we're going to be going through open angle glaucoma.

And you can find written notes on this topic at zero to finals.com slash open angle glaucoma or in the ophthalmology section of the second edition of the zero to finals medicine book.

And you can find flashcards and questions to train your knowledge and help you remember the information for longer at members.0 to

finals.com. So let's get straight into it. Glorcoma refers to the optic nerve damage that's

caused by a rise in intraocular pressure, the pressure inside the eye. Raised intraocular pressure

is caused by a blockage in aqueous humour trying to drain away from the

eye.

There are two types of glaucoma, open angle glaucoma and acute angle closure glaucoma.

Let's start with the basic anatomy and physiology. The anterior chamber, which is between

the cornea and the iris, and the posterior chamber, which is between the lens and the iris,

are filled with aqueous humor. Aqueous humor supplies nutrients to the cornea. It's produced by the ciliary body and it

flows from the posterior chamber around the iris to the anterior chamber of the eye. It drains through

the trabecular meshwork into the canal of Schlem at the angle between the cornea

and the iris. From there it enters the general circulation. A normal intraocular pressure

is between 10 and 21 millimeters of mercury and this is created by the resistance to flow through the trabecular

meshwork as the aqueous humor drains out. An increased resistance to flow through the

trabecular meshwork will result in an increased intraocular pressure. Let's talk about the pathophysiology.

With open angle glaucoma, there is a gradual increase in resistance

to flow through the trabecular meshwork. The pressure slowly builds within the eye. Raised intraocular

pressure causes cupping of the optic disc. In the center of the optic disc is an indent that's called the optic cup.

The optic cup is usually less than 50% of the size of the optic disc.

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