Drugs Used to Treat Glaucoma
Known as the “sneak thief of vision”, glaucoma results in damage to the optic nerve which, over time, leads to vision loss and permanent blindness. Here, we review the drugs used to treat glaucoma – the facts you need to know.
As part of your pharmacy exam, you will be expected to have a solid knowledge of many disease states. Glaucoma is one such example. Prepare for NAPLEX practice questions on this topic as it is bound to appear on your clinical pharmacy exam.
Below, we review the following details on glaucoma:
- Definition / classification
- Causes of glaucoma
- Treatment options
Let’s get started.
What is Glaucoma
In normally functioning eyes, aqueous fluid flows through a mesh-like network called the trabecular meshwork.
In glaucoma, this fluid is either overproduced or has difficulty escaping the eye – leading to accumulated ocular pressure. Over time, this pressure damages the optic nerve, leading to vision loss.
There are two main types of glaucoma:
- Open-angle glaucoma – by far the most common type; the version in which the trabecular meshwork is normal but aqueous fluid does not flow out of this meshwork as it should.
- Closed-angle glaucoma – here, the drain space between the cornea and iris narrows, meaning that aqueous fluid accumulates. Closed-angle glaucoma is far more common in Asia than in the West. It is linked to cataracts.
Glaucoma is more common in adults over the age of 40, particularly those who have a family history of the disease or who have other, comorbid conditions such as diabetes type 2. African Americans, Irish, Scandinavian, Russian and Japanese people are more likely to develop glaucoma. For some, trauma to the eyes can trigger the condition.
Symptoms of glaucoma aren’t always obvious; they may instead develop over many years. The classic, initial symptom is gradual peripheral vision loss. In addition, patients may experience eye pain, eye redness, headache and the appearance of halos around lighting. Nausea / vomiting may also be present.
Doctors who suspect glaucoma may perform certain tests. These include tonometry, in which the patient’s ocular pressure is measured. A visual field test may also be performed to establish the degree of peripheral vision loss. A mydriatic may be applied to the pupils to impart dilation, allowing the clinician to view any prospective damage to the optic nerve. Collectively, these tests are used to help diagnose glaucoma.
Treatment options depend on the patient and the severity of their condition. Options include:
- Medication – most commonly through the application of eye drops
- Laser surgery – commonly used in open-angle glaucoma to increase fluid outflow from the eye. It can also be used in closed-angle glaucoma to prevent blockages. Examples include trabeculoplasty (opening drainage sites), iridotomy (hole formation in the iris to allow fluid to flow), and cyclophotocoagulation.
- Microsurgery – surgery known as trabeculectomy in which a new drainage channel is generated to ease eye pressure.
Below, we take a close look at drugs used to treat glaucoma – examples, how they work and what side effects each class is associated with.
Drugs Used to Treat Glaucoma
There are some therapeutic similarities between various drug classes:
- Beta-blockers and carbonic anhydrase inhibitors work by decreasing aqueous humor production.
- Alpha agonists decrease fluid production and increase drainage.
- Rho kinase inhibitors and prostaglandin analogs increase fluid outflow from the eye.
Below, we’ve tabulated the fundamental pharmacology of glaucoma that you need to know.
|Drug Class||Examples||Side Effects|
|Low blood pressure
Shortness of breath*
|Prostaglandin analogs (F2α)||Bimatoprost
|Eye color changes
Sunken eyes / droopy eyelids
Stinging, redness, burning
|Carbonic anhydrase inhibitors||Dorzolamide
|Eye discomfort / stinging
|Rho kinase inhibitors||Netasurdil||Bleeds in white of eye
Note that timolol is a non-selective beta blocker and so it associated with shortness of breath. In contrast, betaxolol is selective for beta-1 receptors.
Also note that many of these medicines are available as combination products.
Here are some of the most common examples:
- Cosopt – timolol and dorzolamide
- Combigan – brimonidine and timolol
- Simbrinza – brinzolamide and brimonidine
Learning about the clinical pharmacology of glaucoma doesn’t need to be difficult. Here, we put together an introductory guide on the fundamental details that you need to know.
Commit these details on drugs used to treat glaucoma to memory and build upon them in the weeks and months ahead. That way, you are fully prepared for the needs of your next clinical pharmacy exam.
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