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![DRUGS THAT DECREASE AQUEOUS PRODUCTION
I. Beta-Blockers [levobunolol, timolol, carteolol, betaxolol]
-Mechanism: Act on ciliary body to ↓ production of aqueous humor
-Administration: Topical drops to avoid systemic effects
-Side Effects: Cardiovascular (bradycardia, asystole, syncope), bronchoconstriction
(avoid with β1-selective betaxolol)
I. Alpha-2 Adrenergic Agonists [apraclonidine, brimonidine]
-Mechanism: ↓ production of aqueous humor
-Administration: Topical drops
-Side Effects: Lethargy, fatigue, dry mouth [apraclonidine is a derivative of clonidine
(antihypertensive) which cannot cross BBB to cause systemic hypotension]
I. Carbonic Anhydrase Inhibitors [acetazolamide,dorzolamide]
-Mechanism: Blocks CAII enzyme production of bicarbonate ions (transported to
posterior chamber, carrying osmotic water flow), thus ↓ production of
aqueous humor
-Administration: Oral, topical
-Side Effects: malaise, kidney stones, possible (rare) aplastic anemia](https://image.slidesharecdn.com/glaucoma-180801141206/85/Glaucoma-14-320.jpg)
![DRUGS THAT INCREASE AQUEOUS OUTFLOW
I. Nonspecific Adrenergic Agonists [epinephrine, dipivefrin]
-Mechanism: ↑ uveoscleral outflow of aqueous humor
-Administration: Topical drops
-Side Effects: Can precipitate acute attack in patients with narrow iris-corneal angle,
headaches & cardiovascular arrhythmia
I. Parasympathomimetics (pilocarpine, carbachol)
-Mechanism: ↑ contractile force of ciliary body muscle, ↑ outflow via
-Administration: Topical drops or gel, (slow-release plastic insert)
-Side Effects: Headache, induced miopia. Few systemic SE for direct-acting agonists
vs. AchE inhibitors (diarrhea, cramps)
I. Prostaglandins [latanoprost]
-Mechanism: May ↑ uveoscleral outflow
-Administration: Topical drops
-Side Effects: Iris color change](https://image.slidesharecdn.com/glaucoma-180801141206/85/Glaucoma-15-320.jpg)
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Glaucoma
- 1.
- 2. What is glaucoma? •Optic neuropathy that is the leading cause of irreversible blindness in the world • Major types are open angle and closed angle • Differences among various types of glaucoma complicate the nomenclature • Glaucoma is commonly associated with elevated intraocular pressure (IOP), but the disease can occur in the context of normal IOP (normal iop-10-22mm Hg) • Our understanding and treatment of the disease is very focused on IOP
- 3. Types of glaucoma I.Primary: A. Congenital B. Hereditary C. Adult (common types) 1. Narrow angle 2. Open angle II. Secondary A. Inflammatory B. Traumatic
- 4. Congenital Glaucoma Onset: antenatallyto 2 years old SymptomsSymptoms IrritabilityIrritability PhotophobiaPhotophobia EpiphoraEpiphora Poor visionPoor vision Signs Elevated IOP Buphthalmos Haab’s striae Corneal clouding Glaucomatous cupping Field loss
- 5. Congenital Glaucoma Buphthalmos andcloudy corneasBuphthalmos and cloudy corneas
- 6.
- 7. Open Angle Glaucoma Fromhttp://www.merckfrosst.ca/e/health/glaucoma/glaucoma/classify/home.html • Obstruction at the level of the trabecular meshwork • Progressive loss of visual field over time from periphery to center • Presence of hollowed out optic disc (‘cupping’) due to retinal ganglion cell death • Open anterior chamber angle • Majority of patients have IOP > 21 mmHg, asymptomatic
- 8. Open Angle Glaucoma Chronicsimple glaucoma (CSG) and primary open angle glaucoma (POAG) Risk Factors IOP Diabetes Age Myopia Race Gender Family history Cardiovascular Central corneal disease thickness Hormones
- 9. Open Angle Glaucoma Onset:50+ years of ageOnset: 50+ years of age SymptomsSymptoms Usually noneUsually none May have loss of centralMay have loss of central and peripheral visionand peripheral vision latelate SignsSigns Elevated IOPElevated IOP Visual field lossVisual field loss Glaucomatous disk changesGlaucomatous disk changes
- 10. Closed Angle Glaucoma •Apposition of iris and trabecular meshwork • Parasympatholytics (pupillary dilation) can precipitate attack • Increase risk with age, increase in volume of lens • Acute onset, patient complains of nausea, headache (rather than eye ache), malaise, general distress • Requires immediate treatment
- 11. Closed Angle Glaucoma Onset:50+ years of ageOnset: 50+ years of age SymptomsSymptoms Severe eye/headacheSevere eye/headache painpain Blurred visionBlurred vision Red eyeRed eye Nausea and vomitingNausea and vomiting Halos around lightsHalos around lights Intermittent eye acheIntermittent eye ache at nightat night SignsSigns Red, teary eyeRed, teary eye Corneal edemaCorneal edema Closed angleClosed angle Mid-dilated, fixedMid-dilated, fixed pupilpupil Iris atrophyIris atrophy
- 12. BOTTOM LINE: ↑IOPfrom ↓Aqueous Flow, 3 Sites 1. Obstructed Trabecular Mesh Open Angle: Age-related, genetic Closed Angle: Anatomic, exacerbated by: 2. Pupillary Block Dilation of pupil→ iris flattens, ↓ flow via pupil, iris forward ↓iris-cornea angle 3. Swelling of Ciliary Body 1 2 3 Modified from: Wood et al. NEJM 339:1298 (1998)
- 13. TREATMENT RATIONALE LOWER IOPBY: (1) Decreasing Production of Aqueous Humor (2) Increasing Outflow of Aqueous Humor
- 14. DRUGS THAT DECREASEAQUEOUS PRODUCTION I. Beta-Blockers [levobunolol, timolol, carteolol, betaxolol] -Mechanism: Act on ciliary body to ↓ production of aqueous humor -Administration: Topical drops to avoid systemic effects -Side Effects: Cardiovascular (bradycardia, asystole, syncope), bronchoconstriction (avoid with β1-selective betaxolol) I. Alpha-2 Adrenergic Agonists [apraclonidine, brimonidine] -Mechanism: ↓ production of aqueous humor -Administration: Topical drops -Side Effects: Lethargy, fatigue, dry mouth [apraclonidine is a derivative of clonidine (antihypertensive) which cannot cross BBB to cause systemic hypotension] I. Carbonic Anhydrase Inhibitors [acetazolamide,dorzolamide] -Mechanism: Blocks CAII enzyme production of bicarbonate ions (transported to posterior chamber, carrying osmotic water flow), thus ↓ production of aqueous humor -Administration: Oral, topical -Side Effects: malaise, kidney stones, possible (rare) aplastic anemia
- 15. DRUGS THAT INCREASEAQUEOUS OUTFLOW I. Nonspecific Adrenergic Agonists [epinephrine, dipivefrin] -Mechanism: ↑ uveoscleral outflow of aqueous humor -Administration: Topical drops -Side Effects: Can precipitate acute attack in patients with narrow iris-corneal angle, headaches & cardiovascular arrhythmia I. Parasympathomimetics (pilocarpine, carbachol) -Mechanism: ↑ contractile force of ciliary body muscle, ↑ outflow via -Administration: Topical drops or gel, (slow-release plastic insert) -Side Effects: Headache, induced miopia. Few systemic SE for direct-acting agonists vs. AchE inhibitors (diarrhea, cramps) I. Prostaglandins [latanoprost] -Mechanism: May ↑ uveoscleral outflow -Administration: Topical drops -Side Effects: Iris color change
- 16. Rx GLAUCOMA: ADDITIONALCONSIDERATIONS 1. No single medication can be used in all patients 2. Compliance - Critical: Rx often requires several agents, multiple times a day, everyday - Role of slow-release drug delivery devices (Langer) 3. Non-pharmacologic ways to lower IOP: - Laser (argon laser trabeculoplasty) - ↑ aqueous outflow, loses effectiveness over time - Surgical (trabeculectomy) - Creates alternative path for aqueous outflow - Only definitive therapy for closed angle 4. Effectiveness of Rx measured by ability to lower IOP, but other factors may be (more) important: - Neuroprotection/increased blood flow to optic nerve
- 17. GLAUCOMA: Key Points •Glaucoma: -Visual loss from optic neuropathy -Open angle chronic, Closed angle acute -Final common pathway: ↑ IOP (usually) • Drug Rx: -All directed towards ↓IOP either via: - ↓ aqueous production: Beta blockers Alpha-2 agonists Carbonic anhydrase inhibitors - ↑ aqueous outflow: (Adrenergic agonists, nonspecific) Parasympathomimetics Prostaglandins • Treatment slows progression
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Editor's Notes
- #3 The diversity of diseases that fall under the name ‘glaucoma’ make a precise definition of the disease hard to come by. Most clinicians call any condition in which the intraocular pressure is elevated glaucoma. But, this is not a sufficient definition of the disease. Glaucoma is not a single entity. Glaucoma is the leading cause of irreversible blindness in this country However, our understanding of the disease and approach to treatment is very centered around the intraocular pressure. As such, it is important that we understand the dynamics of aqueous humor flow.
- #5 Haab’s striae are found only in congenital glaucoma.
- #6 The right eye in each patient has congenital glaucoma.
- #7 In order to understand the two subtypes of the disease that are the focus of today’s case, we must understand the dynamics of aqueous humor production and flow. Disruption of this process can result in elevated IOP and contribute to the pathogenesis of glaucoma. The aqueous humor is secreted by the ciliary body. Produced by a combination of active transport of ions and ultrafiltration of interstitial fluid. The fluid flows over the surface of the lens, out through the pupil into the anterior chamber. Flows through the trabecular meshwork into Schlemm’s canal and is collected in the scleral veins. Seeing this flow pattern, you can imagine how problems can occur and result in accumulation of fluid and elevated pressure.
- #8 In open angle glaucoma, there is an obstruction at the level of the trabecular meshwork obstructing flow. In closed angle, the lens pushes forward impeding flow through the pupil. This creates a pressure gradient across the iris pushing the iris forward mechanically blocking the trabecular meshwork resulting in a block of aqueous humor flow and elevated intraocular pressure. Although patients with open angle glaucoma may have elevated pressure, they generally do not perceive it- likely because this elevated pressure has developed slowly over time rather acutely, as is the case in closed angle
- #10 Remember: most patients with open angle glaucoma have no symptoms. This is the best reason to have periodic eye examinations with pressure checks and optic nerve evaluations.
- #11 There is a lifelong increase in the volume of the lens. In our case, dilation of the pupil caused the iris to dilate and resulted in angle closure. This person already had a predisposition. Acute angle closure attacks can also occur with the administration of systemic parasympatholytic agents. These agents dilate the pupil and induce iridotrabecular contact The patient appears to be generally in distre
- #12 The classical signs and symptoms of narrow angle glaucoma.