Eye Health Spotlight Tackling Glaucoma with Modern Care
This episode dives into glaucoma, focusing on its types, symptoms, and management. Learn about open-angle glaucoma, acute angle closure glaucoma, and surgical and medical treatments to prevent vision loss. Transcript 00:00] Hello and welcome back to Surgery 101. The podcast brought to you with the help of the Department of Surgery at the University of Alberta. My name is Jonathan White and I’m a surgeon here at the Royal Alex [00:20] Sandra Hospital in Edmonton. This week’s episode is the second in a series of five episodes all about the eye, brought to us by medical student Kim Papp. Last week we covered the basic structure and function of the eye. This week we get to feast our eyes on the topic of blood coma. We’ll be looking at the [00:40] of the condition, the different sorts that there are and the different treatment options. So let’s get ready to think about what happens when you’ve got a little bit too much pressure in your eye here on surgery 101. [01:00] Glaucoma. Welcome to this episode of Surgery 101 on glaucoma, where we will learn the basics of this common ocular disease. My name is Kim and I am a fourth year medical student at the University of [01:20] Alberta. I’d like to give a huge thanks to Dr. Chris Rudniski for his expert review of this content. Today’s objectives are to 1. Describe the eye anatomy relevant to glaucoma. 2. Understand the pathophysiology, symptoms, and management options for open-angle glaucoma. 3. [01:40] Understand the pathophysiology, symptoms, and management options for acute angle closure glaucoma and, four, list other causes of glaucoma. Definition. Glaucoma is a common eye disease. In glaucoma, patients get optic nerve damage. Glaucoma is associated with [02:00] high eye pressure inside the eye called intraocular pressure, or IOP. Not all cases of glaucoma have high IOP, but it is safe enough for this introductory discussion to think of glaucoma as optic nerve damage with elevated intraocular pressure. The [02:20] The cutoff measurement for high IOP is usually 21 millimeters of mercury. Anatomy. How can you even get high pressure inside the eye? To understand this, we need to discuss aqueous humor and the angle of the anterior chamber. Aqueous humor is the [02:40] that fills up the anterior chamber, which is the space between the cornea and the iris. Aqueous humor is constantly being produced and drained out of the eye, so IOP can rise if aqueous is not being drained effectively. The ciliary body, [03:00] behind the iris produces aqueous humor. You may know that the ciliary body’s second job is to anchor the zonules that suspend the lens. Let’s follow the path of aqueous humor in the eye. The ciliary body produces aqueous from here, aqueous flows in [03:20] front of the lens, forward through the pupil, and into the anterior chamber. From there, aqueous drains into the angle formed by the cornea and the iris into a drainage system called the trabecular meshwork. From the trabecular meshwork, aqueous makes its way into the venous [03:40] system of the body. As an aside, if you are loving this discussion of eye anatomy and physiology, check out our other Surgery 101 podcast episode on eye fundamentals. Open-angle glaucoma. In North America, by far the most common type of glaucoma is open [04:00] open angle glaucoma. This is the type that is screened for at optometry eye exams. You may have experienced the unpleasant puff of air onto your eye when you were looking at the hot air balloon picture. This is one way to measure eye pressure, or IOP. We screen for open angle glaucoma, OAG, [04:20] because most patients with OAG are asymptomatic and because OAG causes gradual vision loss if we don’t intervene with management. What do we mean by open angle? Remember that the angle that we’re talking about here is the angle in the anterior chamber between the core [04:40] Here, aqueous humor drains into the trabecular meshwork. In open-angle glaucoma, the angle is perfectly normal and not too narrow, so the reason for the high IOP isn’t that the drainage angle is closed. So if the angle is [05:00] fine in OAG, what’s causing the high intraocular pressure? The thought here is that with age, there is microscopic dysfunction or clogging of the trabecular meshwork. So in open-angle glaucoma, aqueous humor can’t drain effectively through the trabecular meshwork. [05:20] which raises IOP and damages the optic nerve. The three major findings of chronic open-angle glaucoma are 1. high IOP, 2. optic disc changes, and 3. visual field loss. Let’s break each of these down [05:40] before diving into treatment. As mentioned before, the cutoff for high intraocular pressure is an IOP greater than 21 millimeters of mercury. For optic disc changes, ophthalmologists train to notice subtle changes in the appearance of the optic disc that signify [06:00] damage from glaucoma. One of these is a cup to disc ratio greater than 0.5. The details of this cup to disc ratio are beyond this introductory episode. For visual fields, patients with OAG tend to lose their peripheral vision slowly over time. [06:20] This is why we check their visual fields. To do this, ask the patient to look at your nose and hold out your hands midway between the two of you, holding up either one, two, or five fingers, and ask the patient how many fingers they count. Make sure they’re always looking at your nose and not taking a peek. [06:40] off to the side where your hands are. You can assess how well they see in each quadrant of vision with each eye. Let’s look at management of open-ingle glaucoma. There are many medical treatment options in the form of eye drops that are first line. These include topical prostaglandin and [07:00] beta blockers, alpha agonists, and carbonic anhydrase inhibitors. Since this podcast is with Surgery 101, however, we will focus our discussion on understanding some surgical