OPHTHALMOLOGY Glaucoma

MBChB 4 Prof P Roux 2012

WHAT IS GLAUCOMA?

•A GROUP OF DISEASES IN WHICH INTRAOCULAR PRESSURE (IOP) CAUSES DAMAGE TO VISION.

COMMON FEATURES:

•Optic disc cupping •Visual field loss •Raised intraocular pressure (Usually)

AQUEOUS HUMOUR DYNAMICS: PRODUCTION OUTFLOW

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SECRETION

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ULTRAFILTRATION

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TRABECULAR MESHWORK (ANGLE)

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UVEOSCLERAL PATHWAY

Aqueous outflow Anatomy Physiology a - Uveal meshwork b - Corneoscleral meshwork c - Schwalbe line d - Schlemm canal e - Collector channels f - Longitudinal muscle of ciliary body g - Scleral spur a - Conventional outflow b - Uveoscleral outflow c - Iris outflow

ANGLE

CLASSIFICATION:

ACCORDING TO: ASSOCIATED FACTORS •OPEN-ANGLE •ANGLE-CLOSURE •PRIMARY •SECONDARY AGE OF ONSET •CONGENITAL •INFANTILE •JUVENILE •ADULT

c a

ANGLE

b Open-angle a. Pre-trabecular - membrane over trabeculum b. Trabecular - ‘clogging up’ of trabeculum d Angle-closure c. With pupil block - seclusio pupillae and iris bombé d. Without pupil block - peripheral anterior synechiae

ASSOCIATED FACTORS

SECONDARY GLAUCOMAS 1. Pseudoexfoliation glaucoma 2. Pigmentary glaucoma 3. Neovascular glaucoma 4. Inflammatory glaucomas 5. Phacolytic glaucoma 6. Post-traumatic angle recession glaucoma 7. Iridocorneal endothelial syndrome 8. Glaucoma associated with iridoschisis

PATHOGENESIS

•INDIRECT ISCHAEMIC THEORY (MICROCIRCULATION/ PERFUSION PRESSURE) •DIRECT MECHANICAL THEORY (DAMAGE TO NERVE FIBRES)

Theories of glaucomatous damage Direct damage by pressure Capillary occlusion Interference with axoplasmic flow

Risk Factors 1. Age - most cases present after age 65 years 2. Race - more common, earlier onset and more severe in blacks 3. Inheritance

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Level of IOP, outflow facility and disc size are inherited

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Risk is increased by x2 if parent has POAG Risk is increased x4 if sibling has POAG 4. Myopia 5. Diabetes

EXAMINATION

1. TONOMETRY (PRESSURE) 2. GONIOSCOPY (ANGLE) 3. VISUAL FIELD 4. OPTIC DISC (OPTIC NERVE)

Tonometers Goldmann Contact applanation Perkins Portable contact applanation Schiotz Contact indentation Air-puff Non-contact indentation Pulsair 2000 (Keeler) Portable non-contact applanation Tono-Pen Portable contact applanation

Goniolenses Goldmann Zeiss

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Single or triple mirror Contact surface diameter 12 mm

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Coupling substance required Suitable for ALT

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Four mirror Contact surface diameter 9 mm Coupling substance not required Not suitable for ALT

Indentation gonioscopy Differentiates ‘appositional’ from ‘synechial’ angle closure Press Zeiss lens posteriorly against cornea Aqueous is forced into periphery of anterior chamber

Humphrey perimetry

Anatomy of retinal nerve fibres Papillomacular bundle Horizontal raphe

c a b Optic nerve head Small physiological cup a - Nerve fibre layer b - Prelaminar layer c - Laminar layer Large physiological cup

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Normal vertical cup-disc ratio is 0.3 or less

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2% of population have cup-disc ratio > 0.7

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Asymmetry of 0.2 or more is suspicious Total glaucomatous cupping

Types of physiological excavation Small dimple central cup Larger and deeper punched-out central cup Cup with sloping temporal wall

Pallor and cupping Pallor - maximal area of colour contrast Cupping - bending of small blood vessels crossing disc Cupping and pallor correspond Cupping is greater than pallor

TREATMENT OF GLAUCOMA

1 2 MEDICAL SURGERY Trabeculectomy LASER 3

ANTIGLAUCOMA DRUGS

1. ALPHA-2 SELECTIVE ADR. AGONISTS - Alphagan 2. BETA-ADRENERGIC BLOCKING AGENTS - Betagan 3. CARBONIC ANHYDRASE INHIBITORS - Trusopt 4. PROSTAGLANDIN DERIVATIVES - Xalatan 5. PILOCARPINE 6. ADRENALINE

DECREASED AH PRODUCTION

•ADRENERGIC AGONISTS -ALPHA-2 •ADRENERGIC ANTAGONISTS -BETA BLOCKERS •CAI

INCREASED OUTFLOW

•ADRENERGIC AGONISTS (NON SELECTIVE) •PILOCARPINE •PROSTAGLANDINE DERIVATIVES

ANGLE GLOSURE GLAUCOMA

• • • • • ACUTELY PAINFULL RED EYE !!

LOSS OF VA , CLOUDY CORNEA, NON REACTIVE PUPIL, LOSS OF RED REFLEX

MANAGEMENT

• DIAGNOSIS • TOPICAL & SYSTEMIC PRESSURE REDUCTION • PILOCARPINE (REDUCE PUPIL BLOCK) • SYSTEMIC ANALGESIC & ANTI-EMETICS • LASER PI

SURGERY: Technique a b a. Cutting of deep block anterior incision c b. Posterior incision d c. Excision of deep block e d. Peripheral iridectomy f e. Suturing of flap and reconstitution of anterior chamber f. Suturing of conjunctiva

OPEN ANGLE ANGLE CLOSURE GLAUCOMA SECONDARY GLAUCOMAS

Port-wine stain Sturge-Weber syndrome Naevus flammeus Meningeal haemangioma

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Congenital, does not blanche with pressure

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Associated with ipsilateral glaucoma in 30% of cases

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CT scan showing left parietal haemangioma Complications - mental handicap, epilepsy and hemiparesis

Fibroma molluscum in NF-1

Iris melanoma

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Usually pigmented nodule at least 3 mm in diameter

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Invariably in inferior half of iris Occasionally non-pigmented Surface vascularization

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Angle involvement may cause glaucoma

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Pupillary distortion, ectropion uveae and cataract