Lab 1 - Glaucoma

Question 1

List the 3 theories of glaucoma pathophysiology

Answer 1

1. Mechanical
2. Ischaemic
3. Excitotoxicity

Question 2

Describe the mechanical theory of glaucoma pathophysiology

Answer 2

Deformation of lamina cribrosa plates as a result of increased IOP directly compresses nerve fibres, leading to blockage of axoplasmic flow and leading to cell death.

Question 3

Describe the ischaemic theory of glaucoma pathophysiology

Answer 3

Insufficient blood supply to the ONH results in ischaemic injury and decrease in axonal transport rate

Question 4

Describe the excitotoxicity theory of glaucoma pathophysiology

Answer 4

Increased levels of glutamate contributes to RGC death and damage

Question 5

Describe the changes seen in a glaucomatous patient under fundoscopy

Answer 5

• Optic disc haemorrhage
• ONH notching
• RNFL wedge defect
• Bayonetting of blood vessels
• ISNT rule defiance
• laminar dot sign

Question 6

Describe the tests that make up the key elements of a glaucoma workup (7)

Answer 6

1. History taking
2. IOP measurement (Goldmann tonometry)
3. Ocular examination (fundoscopy) of the ONH
4. Central corneal thickness (CCT)
5. Gonioscopy
6. Visual fields
7. OCT

Question 7

Describe the pathophysiology of pigment dispersion syndrome/glaucoma

Answer 7

Posterior bowing of peripheral iris pushes iris epithelium onto lens zonules

Mechanical rubbing of posterior iris epithelium leads to deposition of pigment on lens, corneal epithelium and trabecular meshwork, causing blockage and increase IOP

Question 8

Describe the pathophysiology of pseudoexfoliation syndrome/glaucoma

Answer 8

Grey/white pseudoexfoliative material deposited onto lens, cornea and blocks trabecular meshwork

Question 9

Describe the pathophysiology of corticosteroid induced glaucoma

Answer 9

Corticosteroids increase IOP by decreasing AH outflow, leading to glaucoma

Question 10

Describe the pathophysiology of inflammatory glaucomas

Answer 10

Without pupillary block - deposition of inflammatory cells and debris into the angle

With pupillary block - iris bombe = outflow blocked

Question 11

Describe what you would observe upon examination of a patient with pigment dispersion syndrome

Answer 11

• Posterior bowing of peripheral iris
• Krukenber’s spindle (pigment on corneal endothelium)
• Iris transillumination
• dense pigmentation of TM
• Scheie stripe (pigment along insertion of zonule fibre)

Question 12

Describe what you would observe upon examination of a patient with pseudoexfoliation syndrome

Answer 12

• Grey/white material on lens, cornea, TM
• transillumination defects at pupil ruff of iris
• Sampaolesi line (blotchi pigmentation at or anterior to schwalbe’s line)