Podcast
Questions and Answers
What is the primary mechanism causing angle closure in the eye?
What is the primary mechanism causing angle closure in the eye?
Which risk factor is commonly associated with primary angle-closure glaucoma?
Which risk factor is commonly associated with primary angle-closure glaucoma?
Which surgical treatment option frequently results in a significant fall in intraocular pressure (IOP)?
Which surgical treatment option frequently results in a significant fall in intraocular pressure (IOP)?
What specific patient demographic is most affected by primary angle-closure glaucoma?
What specific patient demographic is most affected by primary angle-closure glaucoma?
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Which of the following statements about beta blockers is false?
Which of the following statements about beta blockers is false?
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What is a primary characteristic of Primary Open Angle Glaucoma (POAG)?
What is a primary characteristic of Primary Open Angle Glaucoma (POAG)?
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Which symptom is most commonly associated with glaucoma in its early stages?
Which symptom is most commonly associated with glaucoma in its early stages?
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What does the evaluation of optic disc cupping mainly focus on?
What does the evaluation of optic disc cupping mainly focus on?
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Which of the following structures is NOT typically visible during an examination of the anterior chamber angle with a Goniolens?
Which of the following structures is NOT typically visible during an examination of the anterior chamber angle with a Goniolens?
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What would NOT be an expected finding in the pathophysiology of glaucoma?
What would NOT be an expected finding in the pathophysiology of glaucoma?
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What characterizes Vogt's triad in postcongestive primary angle closure?
What characterizes Vogt's triad in postcongestive primary angle closure?
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Which surgical complication is NOT associated with glaucoma surgery?
Which surgical complication is NOT associated with glaucoma surgery?
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What condition results from anterior displacement of the lens causing angle blockage?
What condition results from anterior displacement of the lens causing angle blockage?
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Which factor is NOT related to congenital glaucoma?
Which factor is NOT related to congenital glaucoma?
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Which of the following treatments is commonly used for painful blind eyes resulting from neovascular glaucoma?
Which of the following treatments is commonly used for painful blind eyes resulting from neovascular glaucoma?
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What is the classification of glaucoma that manifests after the third birthday but before 16 years of age?
What is the classification of glaucoma that manifests after the third birthday but before 16 years of age?
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Which symptom is commonly observed in the early stages of glaucoma?
Which symptom is commonly observed in the early stages of glaucoma?
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During the treatment of glaucoma, which procedure is typically performed if the cornea is clear?
During the treatment of glaucoma, which procedure is typically performed if the cornea is clear?
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What is the purpose of Anterior Segment OCT in glaucoma investigations?
What is the purpose of Anterior Segment OCT in glaucoma investigations?
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What feature distinguishes micro invasive glaucoma surgery (MIGS) from traditional glaucoma surgeries?
What feature distinguishes micro invasive glaucoma surgery (MIGS) from traditional glaucoma surgeries?
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What is a common initial symptom of acute angle-closure glaucoma (AACG)?
What is a common initial symptom of acute angle-closure glaucoma (AACG)?
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Which diagnostic test is specifically used to evaluate the anterior chamber angle?
Which diagnostic test is specifically used to evaluate the anterior chamber angle?
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What is the characteristic finding in gonioscopy for patients with AACG?
What is the characteristic finding in gonioscopy for patients with AACG?
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Which treatment option is typically recommended immediately following an acute attack of AACG?
Which treatment option is typically recommended immediately following an acute attack of AACG?
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What signifies a positive result in provocative testing for pupillary block?
What signifies a positive result in provocative testing for pupillary block?
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Which of the following is NOT a common symptom associated with acute angle-closure glaucoma?
Which of the following is NOT a common symptom associated with acute angle-closure glaucoma?
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Which urgent management strategy is used to temporarily reduce aqueous humor production?
Which urgent management strategy is used to temporarily reduce aqueous humor production?
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What role does topical pilocarpine play in the treatment of AACG?
What role does topical pilocarpine play in the treatment of AACG?
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Study Notes
Drainage of Aqueous Humor
- Passive diffusion accounts for 40% of aqueous humor formation.
Classification of Glaucoma
- Primary vs Secondary: Based on the cause, such as genetics or underlying eye conditions.
- Open vs Closed: Determined by the angle anatomy, specifically whether the angle is open or closed.
- Adult, Juvenile, Infantile: Defined by the age of onset of the condition.
Primary Open Angle Glaucoma (POAG)
- Definition: Characterized by an open, normal appearing anterior chamber angle along with elevated intraocular pressure (IOP).
- Features: Optic nerve cupping and visual field defects, caused by retinal ganglion cell loss.
General Pathology of POAG
- Narrowed spaces between trabecular beams
- Reduced trabecular endothelial cells
- Loss of phagocytic activity in trabecular endothelial cells
- Narrowing of collector channels
- Closure of Schlemm's Canal
- Thickening of the scleral spur
Symptoms of POAG
- Typically asymptomatic in early stages.
- Most patients are diagnosed during routine eye exams.
- Late-stage symptoms may include:
- Eye ache
- Headache
- Delayed dark adaptation time
- Frequent need for reading glasses adjustments
Diagnosis of POAG
- Elevated Intraocular Pressure (IOP)
- Open, normal appearing anterior chamber angle
- Characteristics of optic disc damage
- Visual function impairment on perimetry
IOP Measurement
- Goniolens: Used to examine the anterior chamber angle.
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Goniolens visualization:
- Schwalbe's line
- Trabecular meshwork
- Scleral spur
- Base of ciliary body
- Root of the iris
Evaluating Optic Disc Cupping
- High cup:disc ratio
- Asymmetry in cup:disc ratio between eyes
- Splinter hemorrhage
- Anterior uveitis
POAG Treatment
- Beta Blockers: May cause bronchospasm, heart block, or bradycardia.
Surgical Treatment
- Laser Trabeculoplasty (SLT)
- Trabeculectomy
- Trabeculotomy
- Shunt procedures (e.g., Ahmad valve)
- Cyclodestructive procedures
- Phacoemulsification: Can be combined with a filtration procedure (phacotrabeculectomy)
Primary Angle Closure Glaucoma (PACG)
- Incidence of blindness higher than open-angle glaucoma.
- Less common than open-angle glaucoma.
- Affects 0.17% of individuals younger than 40 years, particularly East Asians.
PACG Risk Factors
- Age: Average at presentation 50-60 years.
- Gender: More common in females (4:1 ratio).
- Race: Common in Southeast Asian populations and black Africans.
- Heredity: First-degree relatives have an increased risk.
- Refractive error: More common in hypermetropes.
PACG Pathology
- Angle closure: Occurs when the peripheral iris contacts the trabecular meshwork (TM).
- Two categories of angle closure mechanisms:
- Push: Relative pupillary block, enlarged or anteriorly displaced lens.
- Pull: Iris pulled into contact with TM by inflammatory membranes (uveitis), fibrovascular tissue (iris neovascularization), or chronic intermittent friction.
- Synechiae formation: Adhesions form between the iris and the TM due to chronic friction.
- Impaired aqueous outflow: Dysfunctional or obstructed TM leads to increased IOP.
Clinical Features of Acute Angle-Closure Glaucoma (AACG)
- Halos around lights
- Elevated IOP
- Corneal edema
- Aching eye or brow pain
- Headache
- Nausea, vomiting
- Reduced acuity
- Eye redness
- Engorged conjunctival vessels
- Fixed dilated pupil
- Closed angle on gonioscopy
Diagnostic Tests for AACG
- Slit-lamp examination
- Gonioscopy examination of anterior chamber angle
- Fundoscopy evaluation of optic nerve head
- Anterior segment optical coherence tomography (OCT) of angle
- Automatic static perimetry
- Ultrasound biomicroscopy
- Retinal OCT
Provocative Tests for AACG
- Purpose: Induce pupillary block to assess angle closure.
- Positive test: IOP increase of 8 mmHg or more.
-
Types of tests:
- Dark room test: Patient remains in a dark room for 1-2 hours.
- Prone test: Patient lies in a prone position for 1-2 hours.
- Mydriatic eye drops: Dilate pupils to increase pupillary block.
Treatment Options for PACG
Acute (Initial Presentation)
- Topical prostaglandin analog
- Topical beta-blocker
- Topical alpha-2 agonist
- Carbonic anhydrase inhibitors
- Lens extraction surgery
- Trabeculectomy or tube shunt
Chronic
- Oral carbonic anhydrase inhibitors
- Topical beta-blocker
- Topical alpha-2 agonist
- Topical cholinergic agonists
- Hyperosmotic agents
- Laser peripheral iridotomy (after corneal edema subsides, following an acute attack)
- Lens extraction (after corneal edema subsides, following an acute attack)
Urgent Management of PCAG
- Intravenous acetazolamide (500 mg): Reduces aqueous humor production.
- Intravenous mannitol (1-2 grams/kg): Reduces IOP.
- Topical beta-blocker (timolol 0.5%): Reduces aqueous humor production.
- Topical alpha-2 agonist (apraclonidine 1%): Reduces aqueous humor production.
- Topical pilocarpine (1-2%): Increases aqueous humor outflow.
- Monitor IOP every hour.
Medical Treatment for PACG
Complications of Glaucoma Surgery
Cyclodestructive Surgery
- Hypotony
- Retinal detachment
- Phthisis
Filtering Surgery
- Hyphema (blood in anterior chamber)
- Over or under filtration
- Blebitis (inflamed bleb)
- Scleral flap leak
- Tube lens touch
- Endothelial tube touch
- Endophthalmitis
Vogt's Triad
- Postcongestive primary angle closure
-
Characteristics:
- Glaucomflecken (anterior subcapsular lens opacity)
- Patches of iris atrophy
- Slightly dilated, non-reacting pupil (due to sphincter atrophy)
Secondary Angle Closure Glaucoma
Neovascular Glaucoma (NVG)
- Devastating, severe disease leading to blindness.
- Causes fibrovascular proliferation in the eye (new blood vessels on iris and angle).
- Resul in painful blind eye.
- Treatment: Cyclocryo or diode therapy.
Phacomorphic Glaucoma
- Anterior displacement of the lens causes angle blockage.
Congenital Glaucoma (Buphthalmos)
- Elevated IOP due to congenital angle anomalies.
-
Incidence:
- Bilateral in 70% of cases.
- More common in boys (65%).
- Usually presents before 6 months of age (80%).
- Family history and inherited (autosomal recessive).
Pathogenesis of Congenital Glaucoma
- Maldevelopment of the anterior chamber (AC) angle: Associated with other eye anomalies.
- Isolated trabeculodysgenesis: A developmental abnormality of the trabecular meshwork.
Classification of Congenital Glaucoma
- True: Elevated IOP develops during fetal life.
- Infantile: Develops before the third birthday.
- Juvenile: Develops after the third birthday but before 16 years old.
Clinical Features of Congenital Glaucoma
Symptoms
- Early: Lacrimation, photophobia, blepharospasm (eyelid spasm).
- Late: Large eye (due to elasticity of the outer coat), hazy cornea.
Signs of Congenital Glaucoma
- Increased horizontal corneal diameter (13-14 mm)
- Haab's striae: Horizontal striae caused by Descemet membrane breaks.
- Corneal haze: Due to corneal edema.
- High IOP
- Fundus examination: Optic disc asymmetry or cupping.
- Gonioscopy: To identify congenital angle anomalies.
Congenital Glaucoma Treatment
-
Goniotomy:
- Performed at the time of diagnosis if the cornea is clear and the angle is easily visualized.
-
Trabeculotomy:
- Performed if the cornea is cloudy or if goniotomy fails.
-
Trabeculectomy:
- Used as a last resort.
Trabeculotomy Procedure
- Conjunctival flap is created.
- Partial-thickness scleral flap.
- Scleral incision is made to expose Schlemm's Canal.
- Harm's trabeculotome is passed along the Schlemm's canal.
- Trabeculotome is rotated to break the canal's inner wall.
Updates in Glaucoma
Investigations
- Anterior Segment OCT (AS-OCT): Uses diode light source to create detailed images of the cornea, angle region, and anterior ciliary body.
- Ultrasound Biomicroscopy: Examines the anterior chamber.
- Hood Report: A comprehensive glaucoma evaluation report.
Operations
- Micro Invasive Glaucoma Surgery (MIGS):
- Safety profile: Lower risk of serious complications.
- Minimal disruption of normal anatomy.
- Ab interno approach: Performed from inside the eye.
- Goal: Achieve meaningful IOP reduction.
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Description
Test your knowledge on the classification and pathology of glaucoma, focusing specifically on Primary Open Angle Glaucoma (POAG). Learn about the drainage of aqueous humor and the impact of various factors on intraocular pressure. Ideal for students of ophthalmology and eye health-related fields.
