Glaucoma Overview Quiz for Healthcare Professionals

Introduction to Glaucoma

• Presented by Sarah Larose, BSc Pharm, Dalhousie College of Pharmacy on November 22, 2023
• This lecture is designed to supplement learning on the PBL case and build upon existing knowledge from anatomy and physiology courses.

Disclaimer

• The lecture is intended for PHAR 1051 in 2024-2025
• The information is as complete and accurate as possible based on resources available at the time.
• Readers should note these slides are intended for use in a larger context, not as standalone material.
• Copying or reproducing these slides without permission is not allowed.

Learning Objectives

• Describe and illustrate the anatomy of the eye
• Explain processes involved in normal intraocular pressure regulation
• Compare and contrast open-angle and closed-angle glaucoma (consider pathophysiology, etiology, risk factors, and clinical presentation)
• List drugs that may precipitate closed-angle glaucoma
• Identify the goals of therapy and outcomes in managing open-angle and closed-angle glaucoma
• Describe management (pharmacological and surgical) of open-angle and closed-angle glaucoma
• Describe the pharmacologic class, mechanism of action, efficacy, most common and serious adverse effects, and precautions of pharmacologic agents used to treat open-angle glaucoma (β-blockers, α-agonists, prostaglandin analogues, carbonic anhydrase inhibitors)

Anatomy Review

• The structure of the eye
• Diagram of the eye with labelled parts and a section illustrating the horizontal section showing components like the iris, cornea, ciliary body, sclera, retina, etc
• Diagram of the eye showing the anatomical pathways of aqueous humor drainage (aqueous humor exits through the trabecular meshwork and uveoscleral route)
• Components to the eye with the aqueous humor drainage pathways labelled

Aqueous Humor Formation

• Diffusion of solutes proportionate to concentration gradient
• Ultrafiltration of water-soluble substances proportionate to osmotic gradient
• Active secretion (80-90%) of various molecules across a concentration gradient within the blood aqueous barrier
• Passive conventional route (80–85%) through the trabecular meshwork to Schlemm's canal
• Nonconventional route (ciliary body to sclera pathway)

Intraocular Pressure (IOP)

• Created by inflow of aqueous humor from the ciliary body and resistance of outflow
• IOP should be a result of equal inflow and outflow rates
• Median IOP is approximately 15.5 +/- 2.5 mmHg
• Factors impacting IOP include heart rate and blood pressure, coughing, neck compression, posture, and circadian rhythm variation
• Increased IOP elevates risks of optic nerve changes and visual field loss

Glaucoma

• A condition characterized by optic neuropathy with distinctive loss of retinal nerve fibers and optic disc changes
• Defined by neuropathy with other signs, that qualify the diagnosis depending on the mechanism of the neuropathy
• Functional features include visual field changes
• Important understanding: Elevated IOP (↑ IOP) does not equate to glaucoma

Optic Disc Changes

• Diagrams illustrating healthy vs. glaucomatous optic discs.
• Healthy optic nerve with normal optic nerve head
• Glaucoma optic nerve with glaucomatous cupping of the nerve head

Glaucoma Types

• Two main glaucoma types: open-angle and closed-angle
• Primary: the most common type of open-angle glaucoma (open angle, closed angle, or narrow angle)
• Secondary glaucoma: arises as a consequence of another condition.
• Congenital glaucoma: arises before birth due to structural or functional anomalies

Epidemiology

• Open-angle glaucoma affects approximately 67 million globally.
• Approximately 400,000 Canadians have open-angle glaucoma.
• 2.7% of Canadians aged 40 years or older are diagnosed with open-angle glaucoma.
• 11% of those above the age of 80 have open-angle glaucoma.
• Closed-angle glaucoma is less common.
• Glaucoma is the 2nd leading cause of blindness and the first leading cause of irreversible blindness.

Etiology of Primary Glaucoma

• Open-Angle: Outflow tract is anatomically open, increase in IOP is a development factor with exact cause unknown. Genetic factors and comorbidities are other factors to consider. There is also optic nerve ischemia, excitotoxicity, and autoimmune reactions
• Closed-Angle: Outflow tract is anatomically obstructed; may occur as a medical emergency because of blockage of the trabecular meshwork and typically happens intermittently. Shallow anterior chamber is a characteristic feature.

Pathophysiology

• Open-Angle: Increased resistance to aqueous humor drainage through the trabecular meshwork is the primary cause of the elevated IOP (and glaucoma)
• Closed-Angle: Mechanical obstruction of the trabecular meshwork drainage pathways by the iris creates a blockage of outflow, and causes an increase in IOP. Another example is the blockage of the anterior chamber outflow

Pathophysiology: Glaucomatous Changes

• Shows normal and then glaucomatous changes associated with optic neuropathy
• Shows different components of the eye in both the normal and abnormal conditions

Risk Factors

• Open-Angle: Increased IOP, older age, race/ethnicity (non-white, particularly black), family history of glaucoma, moderate to high myopia, and low diastolic blood pressure.
• Closed-Angle: Older age, female sex, race/ethnicity (East Asian and Chinese), hyperopia, iris characteristics (thick peripheral iris, anterior iris insertion).

Clinical Presentation

• Open-Angle: Typically asymptomatic until late stages, with symptoms arising as blindness and visual obstruction
• Closed-Angle: Acute attacks may include headache, nausea/vomiting, halos around lights, blurred vision, and eye pain. It may also present as chronic, creeping angle closure with minimal symptoms

Risk Factors: Medications

• Medications that may increase IOP in closed-angle glaucoma, including anticholinergics, topical sympathomimetics, antihistamines, tricyclic antidepressants, low-potency phenothiazines, and others.

POAG Classification - Severity

• Classification system for open-angle glaucoma severity based on IOP, optic nerve head characteristics, and visual field testing

Management of Open-Angle Glaucoma

• The goals of treatment focus on maintaining quality of life, reducing IOP, and resolving or controlling risk factors, slowing progression of disease

Information Sources

• Tertiary: Textbooks, databases (e.g., CPS, RxTx, Therapeutic Choices)
• Secondary: Systematic reviews (e.g., Cochrane Review), clinical practice guidelines from various countries
• Primary: Medical studies (e.g., OHTS, EMGT, CIGTS)

Pharmacy Library Guide

• Information about the Dalhousie University Libraries' pharmacy resources and services

Goals of Therapy

• Maintain quality of life, Reduce IOP, Control risk factors, Slow disease progression, Prevent/minimize ADRs, Prevent or minimize visual field/optic nerve damage

Reduce IOP - What is the Target?

• Discusses the importance of target IOP values in glaucoma management and their relevance to clinical practice

Suggested IOP Targets from "Guidelines"

• Various guidelines provide different recommendations for target IOP. The values and requirements vary based on the suspected stage of the disease and other considerations like the patient’s health history/medical background and family history

Landmark Randomized Controlled Trials for Glaucoma

• A timeline outlining landmark clinical trials conducted to examine the treatment for glaucoma

The Ocular Hypertension Treatment Study (OHT)

• Studies examine whether topical medication delays/prevents the onset of glaucoma in patients with ocular hypertension (OHT)
• Treatment goal is to lower IOP to < 24 mmHg and at least 20% reduction from baseline

The Early Manifest Glaucoma Trial

• Trial examines whether IOP reduction can prevent glaucoma progression in early-stage disease.

Interim Clinical Outcomes in the Collaborative Initial Glaucoma Treatment Study

• Comparing treatments and their effect on lowering IOP and its effect on glaucoma progression

Evidence Summary

• Includes key questions:
• Will topical medication delay/prevent glaucoma onset in patients with Ocular Hypertension (OHT)?
• Will treatment prevent glaucoma progression?
• Does the method of lowering IOP affect glaucoma progression?

What is Target IOP?

• Target IOP is estimated to lower IOP. Estimates vary based on the patient and degree of visual damage done.
• No validated algorithm exists for determining the target IOP, but clinical use still considers it a necessary aspect of care

What is Target IOP?

• This section discusses the considerations clinicians use to determine IOP values as well as factors influencing that calculation, such as the stage of disease and risk of progression, among others.

Treatment Options: Pharmacological

• Introduces pharmacological treatment approaches, includes drug classes, and their general mechanisms of action.

Sites of Medication Activity

• Shows the location and pathways through which various medications in glaucoma therapy act (e.g., aqueous humor production/outflow)

Important Guidance

• Clarifies the need for justifying first-line treatment decisions based on patient characteristics and drug properties

What is "First Line" Treatment?

• Provides a decision process that helps decide which therapy to start with

Topical IOP-lowering medications

• Provides a timeline of medications developed to lower IOP

Available Options

• Groups different treatments by their pharmacological classes, (with examples of medications within each class)

Mechanism of Action

• Summarizes the general mechanisms by which different medication classes decrease intraocular pressure (IOP)

Efficacy

• Provides approximate expected reductions in IOP for various pharmacological classes

Safety

• Lists potential safety considerations, including local and systemic adverse drug reactions (ADRs), for various medication classes

Dosing Frequency

• Discusses the frequency of dosing needed to achieve appropriate therapeutic effects

Treatment Algorithm(s)

• Offers a general algorithm to determine treatment protocols

Adherence

• Highlighting frequent issues with adherence and what types of questions a pharmacist might ask to assess patients’ needs and support adherence to the treatment plan

Pregnancy & Breastfeeding

• Discusses the need to balance risks to the mother and fetus, including the potential for lower IOP values during pregnancy and the possible need to consider temporary treatment discontinuation.
• Examines risk factors for developing negative health outcomes from the use of different drugs during different stages of pregnancy (animal and human studies)

Management of Closed-Angle Glaucoma

• Discusses the management (goals, overview) of closed-angle glaucoma and different treatment options.

Role of the Pharmacist

• Discusses the pharmacist's role in recognizing risk factors for closed-angle glaucoma, identifying signs and symptoms, explaining treatments to patients and directing/referring them appropriate care

References & Resources

• Provides a list of resources (Canadian Glaucoma Guidelines, European Glaucoma Guidelines, clinical practice guidelines, textbooks, specific studies) about glaucoma treatments

Overview

• Highlights stage, severity of disease, removal of underlying causes and the use of laser/surgical interventions for closed-angle glaucoma in addition to the consideration of pharmacologic therapy when managing ongoing elevation in IOP

Nonpharmacological Treatment

• Discusses laser and surgical procedures for glaucoma treatment
• Includes considerations like laser iridotomy
• Describes other treatment options like iridectomy, as well as other cases for managing refractory glaucoma.

Laser Iridotomy

• Illustrates an image demonstrating laser iridotomy

Pharmacologic Adjunct Treatment

• Summarizes the pharmacological considerations for managing chronic angle-closure glaucoma (including reducing IOP, re-opening the angle, and reducing inflammation)

Acute Closed-Angle Glaucoma Tx Summary

• Key points and considerations for managing an acute closed-angle glaucoma attack. Emphasizes the need for immediate treatment, including agents to lower IOP, and awaiting laser/surgical intervention, as well as possible recovery paths if the condition is resolved quickly.

Closed-Angle Glaucoma

• Summarizes different presentation types of narrow-angle with normal IOP and also chronic angle closure

Role of the Pharmacist

• Emphasizes the pharmacist's responsibilities to help in recognizing increased risks for angle-closure glaucoma, evaluating signs and symptoms when they arise, and explaining treatment goals and the treatment plans