Primary Open Angle Glaucoma Flashcards
Define glaucoma.
Chronic progressive optic neuropathy caused by a group of ocular conditions.
What is glaucoma characterized by?
- Traditionally characterized by elevated intraocular pressure
- Associated with visual field loss as damage progresses
What is the normal IOP range?
10-20 mm Hg
Name the 2 types of glaucoma.
Open angle glaucoma
Closed angle glaucoma
Define primary open angle glaucoma.
A subset of the glaucomas defined by an open, normal appearing anterior chamber angle and raised intraocular pressure, with no other underlying disease
What is primary open angle glaucoma characterized by?
Peripheral visual field loss followed by central field loss corresponding to the cupping of the optic disc
Which race is most at risk for POAG?
Africans, Black Americans
Describe the pathophysiology of raised IOP.
-Proliferation of endothelial lining with thickening of basement membrane
-Narrowed intertrabecular spaces and obstruction by accumulated material
-Loss of trabecular endothelial cell (resulting in trabecular beam fusing)
-These increase the resistance to aqueous outflow; drainage is impaired → ↑ IOP
- Due to sustained ↑ IOP; progressive damage
- Direct mechanical damage and ischemic damage
Give 3 risk factors for POAG.
- Raised IOP → glaucomatous optic neuropathy
- Age – prevalence ↑ with older age
- Race – Black
- Positive family history of POAG: 1st degree relative; ↑ if sibling
- Myopia – more susceptible to glaucomatous damage
- Thin central corneal thickness – measurement error
Give 3 signs and symptoms for POAG.
Symptoms
- Painless loss of vision
- Headache
- Visual field changes
Signs
- Reduced visual acuity
- Normal anterior chamber depth
- Sluggish pupil
Give 3 differentials for POAG.
- Primary angle closure glaucoma
- Ocular hypertension
- Normal tension glaucoma
- Steroid induced glaucoma
How is POAG diagnosed? (4)
- Raised intraocular pressure – by Goldmann tonometer
- Cupping of optic disk – fundoscopy
- Visual field defects
Central measured by automated perimetry
Peripheral measured by listers Goldmann perimetry
-Normal anterior angles on gonioscopy - Exaggerated diurnal fluctuation of IOP - >5mmHg is suspected of glaucoma; >8mmHg is confirmation of glaucoma
Name 3 investigations done in POAG.
- Perimetry
- Gonioscopy
- Pachymetry
- Optic coherence tomography of the optic disc
Name 3 classes of drugs that can be used to treat POAG.
Prostaglandins, Beta adrenergic blockers, Carbonic anhydrous inhibitors, Alpha adrenergic agonists, Cholinergic agonists
Name the 2 types of laser trabeculoplasty used to treat POAG.
- Argon laser trabeculoplasty
- Selective laser trabeculoplasty
What is trabeculectomy?
A channel is created from the anterior chamber through the sclera to a subconjunctival space referred to as filtering bleb
What is the prognosis of POAG?
- Good if diagnosed and treated early – most patients recover well.
- Untreated POAG lead to irreversible blindness
Mention 4 complications of POAG.
POAG
- Absolute glaucoma
- Irreversible visual loss
POST-OP
- Post – op shallow AC
- Hyphaema
- Iritis
- Cataract due to accidental injury to the lens
- Endophthalmitis
