Glaucoma Flashcards
What is glaucoma?
A group of progressive optic neuropathies that have characteristic changes at the optic nerve head and retinal nerve fiber later in the absence of optic nerve disease.
Classic triad of glaucoma?
- Increased IOP
- Loss of visual fields
- Cupping of optic disc
Is glaucoma treatable?
Yes
Types of glaucoma?
- Open angle (POAG, NTG, Pigment dispersion, PXF)
- Closed angle
- Secondary (Uvetic, trauma, neovascularization)
Primary open angle glaucoma common in what race?
African- American
Characteristics of glaucoma?
- Optic disc cupping
- Visual field defect- due to loss of retinal ganglion cells.
Risk factors of primary open angle glaucoma?
- Elevated IOP
2, Increasing age - Black race
- Family history of glaucoma
- Myopia
- Migraine an vasospasm
What is pigment dispersion syndrome?
Type of open angle glaucoma, characterized by spontaneous dispersion of pigment granules from the pigment epithelium of the iris, which gets deposited in the anterior segment.
How does pigment dispersion syndrome look on retroillumiation and normal exam?
Retroillumination: spoke-like defects
Slit lamp: Pigment granules
What is pseudoexfoliative syndrome (PXF)? How does it look?
Protein like material in anterior segment of the eye, most noticed in the anterior capsule.
Looks like dandruff on the iris bundles. because TBM is blocked.
PDS vs PXF?
Differentiated by pigment deposition in the eye.
PDS: Spindle- shaped pattern (Krukenberg’s spindle) - tends to affect younger myopic patients
PXF: Dandruff like - tends to affect older population.
What is it when patients have increased IOP, Px has no changes vision, but no glaucoma?
Ocular hypertension
How does raised IOP cause optic nerve head damage?
It causes mechanical changes to lamina cribrosa
Eyes not treated for glaucoma IOP can fluctuate upto?
10-15mmHg
True or false? - glaucoma causes stress to the optic nerve head?
True
What happens to optic nerve head in glaucoma?
Alteration of optic nerve head flow and nutrient supply causing retinal ganglion cell death
Why does the neural retinal rim thin?
Due to nerve death
Why does glaucoma cause cupping of optic nerve head?
Nerves die causing the nerve head to excavate.
What regulates IOP in the eye?
Ciliary body- it forms aqueous and drains it to the front and back. For aqueous to move to the anterior chamber it needs to pass through the iris then pas to the pupil and move to the front where it drains through meshwork.
2 places where obstruction of aqueous occurs?
- Pupil block
- Schlemms canal
How is a suspected galucoma confirmed?
Monitor for progression
What is a notch of optic nerve?
Degeneration of blood vessels results in a notch along neuroretinal rim
What is bayoneting of blood vessels in glauacoma?
When blood vessels bend or kink sharply as they pass over the edge of the cup.
It is a sign of erosion or loss of NRR.
True or false- cup/disc ratio varries with disc size?
True
Congenital optic nerve head pit results from? What type of defect does it cause?
Result from an imperfect closure of the superior edge of the embryonic fissure.
It is a small pocket or hole near the optic nerve.
Altitudinal defect
HRT vs OCT- why is OCT better?
OCT allows RNFL + Macular imaging
Relation between pictures and OCT results for glaucoma dignoses?
If OCT and pictures do not match= not glaucoma .
Visual feilds helps identify if thinning is the same place corresposing to picture - if match = glaucoma confirmed
Subtypes of angle closure glaucoma?
- Acute angle closure
- Chronic angle closure
Characteristics of angle closure glaucoma?
- Females > males
- > 40 years
- Painful + vomiting
- Acute loss of vision
- Intermittent blur
- Haloes around bright light
ACG Subtypes/ stages?
- Latent- asymptomatic (IOP normal)
- Subacute- intermittent angle closure (may develop acute or chronic angle closure)
- Acute (Sent to A&E)- Congestive (Sudden total angle closure), Post congestive (follow acute attack)
- Chronic- creeping or latent angle closure
- Absolute - no PL following acute attack
ACG: Predisposing factors?
Convex iris lens diaphragm causes shallow anterior chambers (eclipise sign).
Narrow approach to angle. (Narrow van herick)
ACG Mechanism?
- Increase in physiological pupil block
- Dilation of pupil renders peripheral iris more flaccid.
- Increased pressure in posterior chamber causes iris bombe
- Angle obstruction by peripheral iris and rise in IOP.
What is subacute or intermittent angle closure glaucoma?
brief episodes of angle closure that resolve spontaneously. Patients experience the above symptoms of acute angle closure, but on a milder scale.