Primary Open-Angle Glaucoma
Professor K N Jha,MS
Learning Aim
• Definition of Open-angle glaucoma
• Primary open-angle glaucoma (POAG)
• Clinical features (IOP, fundus, and field
changes) of POAG
• Treatment of POAG
Primary open-angle glaucoma(POAG)
-POAG is characterized by a chronic, slowly
progressive, optic neuropathy with a
characteristic pattern of optic nerve damage
and visual field loss.
-Angle of the anterior chamber is open.
-There are no ocular or systemic disorders.
POAG Risk factors• IOP • Race • Central corneal thickness ( CCT) • Age • Family history• Systemic and ocular associations: DM, Myopia,
HTN, CRVO
POAG: Contributory factors
• Reduced perfusion of the optic nerve head- Inadequate auto-regulation in blood vessels- Mechanical compression of capillaries
• Abnormality of axonal , or ganglion cell metabolism
• Disorders of the extracellular matrix of lamina
cribrosa.
Pathogenesis
• Increased resistance to aqueous outflow• Mechanical changes due to raised IOP
- Decreased axoplasmic flow• Optic nerve head vascular perfusion
- Inadequate autoregulation in blood vessels- Mechanical compression of capillaries
• Glaucomatous Optic atrophy
POAG: Clinical features
• Onset : Insidious, • Slowly progressive, and painless• Bilateral: initially may manifest in one eye.• Visual acuity remains unaffected until late• Diagnosis : IOP, visual fields, and optic disc
appearance.• Gonioscopy: open angles• Associations: myopia, DM, CVS disease, CRVO
Diagnosis
Characteristic optic nerve head changes
Visual field changes
Raised Intraocular pressure (IOP)
At least two of the above three.
Optic disc(ONH) changes in glaucoma
• Increased vertical cup : disc ratio
• Asymmetry of cups between two eyes
• Notching and pallor of neuroretinal rim(NRR)
• Disc hemorrhage
• Baring of circumlinear vessels
• Peripapillary retinal atrophy
Optic Nerve head changes
Normal fundus oculi Glaucomatous cupping
Visual field changes in glaucoma
• Relative paracentral scotoma: smaller/ dimmer targets are not visualized.
• Nasal step: appearance of horizontal shelf in nasal visual field
• Seidel scotoma: starting from one pole of blind spot and arches over macula without reaching horizontal meridian nasally.
• Arcuate scotoma• Double arcuate or ring scotoma• End-stage or near total field defect
POAG : Management
• Early detection and routine screening
• Meticulous documentation: IOP, optic nerve
damage and risk factors
Primary open-angle glaucoma
Treatment goal
• Modify and slow progression of optic nerve
damage.
• To lower IOP
Target pressure
• It is a range of IOP with an upper limit that is
unlikely to lead to further damage.
• Initial reduction: 20% from baseline.
• Target pressure need constant reassessment
dictated by IOP fluctuation , ONH changes,
and/or visual field progression.
Target pressure
Depends on -Initial IOP-Severity of damage-Life expectancy-Associated risk factors like , family history.
POAG: Management
• Patient education
• Cost and Compliance
• Medical or surgical therapy
• Progression and follow-up
POAG: Management
Modalities of treatment
Drug therapy
Laser
Surgery
POAG: Medical Therapy
Topical :
-Parasympathomimetics
-Adrenergic antagonists : beta-blockers
-Sympathomimetics: alpha-2 agonist
-Prostaglandin analogues and hypotensive lipids
CAH inhibitors : Acetazolamide, dorzolamide, brizolamide
Hyperosmotic agents
Primary open-angle glaucoma
• Laser therapy: Argon-laser trabeculoplasty
• Glaucoma surgery: Trabeculectomy
POAG: Prognosis
• Most patients will retain useful vision for their
entire life
• Incidence of blindness at 20 years follow-up is
27 % unilateral, 9 % bilateral.
Primary open-angle glaucoma
Summary:• Clinical features• Fundus changes• Field changes• Diagnosis• Treatment• Follow-up