PRIMARY OPEN-ANGLE GLAUCOMA Indications Technique2. Theories of glaucomatous damage1. Definition and risk factor4. Visual field defects7. Trabeculectomt3. Optic disc cupping5. Medical therapy Filtration blebs Complications6. Laser trabeculoplasty

Definition and risk factorsIOP > 21 mmHgGlaucomatous disc damageOpen angle of normal appearanceVisual field loss

Risk Factors1. Age - most cases present after age 65 years2. Race - more common, earlier onset and more severe in blacks3. Inheritance Level of IOP, outflow facility and disc size are inherited Risk is increased by x2 if parent has POAG Risk is increased x4 if sibling has POAG4. Myopia

Theories of glaucomatous damageDirect damage by pressureCapillary occlusionInterference withaxoplasmic flow

Concentric excavation Diffuse loss of nerve fibres Excavation enlarges concentrically Compare with previous record Initially may be difficult to distinguish from large physiological cup19841994

Localized cupping Focal loss of nerve fibres Notching at superior or more commonly inferior poles Excavation becomes vertically oval Excavation enlarges concentric cupping Nasal displacement of central blood vessels Double angulation of blood vessels (bayoneting sign) Diffuse loss of nerve fibre

Progression of nerve fibre damageNormalSlit defectsWedge defectsTotal atrophy

End-stage damage All neural disc tissue is destroyed Disc is white and deeply excavated Atrophy of all retinal nerve fibres Striations are absent Blood vessels appear dark and sharply defined

Progression of glaucomatous cuppinga. Normal (c:d ratio 0.2)b. Concentric enlargement (c:d ratio 0.5)c. Inferior expansion with retinal nerve fibre losse. Advanced cupping with nasal displacement of vesselsf. Total cupping with loss of all retinal nerve fibresd. Superior expansion with retinal nerve fibre loss

Early visual field defects Small arcuate scotomas Tend to elongate circumferentially Isolated paracentral scotomas Nasal (Roenne) step

Progression of visual field defects Formation of arcuate defects Enlargement of nasal step Development of temporal wedge Peripheral breakthrough Appearance of fresh arcuate inferior defects

Advanced visual field defects Development of ring scotoma Peripheral and central spread Residual temporal island Residual central island

Drugs to treat glaucoma1. Beta blockers2. Sympathomimetics3. Miotics4. Prostaglandin analogues5. Carbonic anhydrase inhibitors Topical Systemic

Laser trabeculoplasty Failed medical therapyIndications Primary therapy in non-compliant patients to junction of pigmented and non-pigmented trabeculum Correct focus with round aiming beam Incorrect focus with oval aiming beam Application of 50-100 burns

Indications for Trabeculectomy1. Failed medical therapy and laser trabeculoplasty Inability to adequately visualize trabeculum3. As primary therapy in advanced disease Poor patient co-operation2. Lack of suitability for trabeculoplasty

Technique (1)a. Conjunctival incisionb. Conjunctival underminingd. Outline of superficial flape. Dissection of superficial flapf. Paracentesisc. Clearing of limbusfdbace

a. Cutting of deep block - anterior incisionb. Posterior incisiond. Peripheral iridectomye. Suturing of flap and reconstitution of anterior chamberf. Suturing of conjunctivac. Excision of deep blockfdbaceTechnique (2)

Filtration blebs Thin and polycysticType 1 Good filtration Relatively avascular Microcysts present Good filtration Flat, thin and diffuseType 2 Engorged surface vessels No microcysts No filtration FlatType 3 Engorged surface vessels No filtration Localized, firm cystEncapsulated

Treatment Options for Failed Trabeculectomy1. Digital massage5. Re-operation2. Laser suture lysis 3. Topical steroids4. Subconjunctival injection of 5-FU6. Re-commence medical therapy

Shallow anterior chamberIOPBleb Seidel testOverfiltration lowgood negativeMalignant glaucoma highpoor negativeWound leak lowpoor positiveCause

Late bleb infection Thin-walled, cystic blebPredispositions Use of adjunctive antimetabolites Milky bleb No hypopyon Good prognosis Subacute onsetBlebitis Bleb trauma Hypopyon Guarded prognosis Acute onsetEndophthalmitis