Understanding Glauco ma

Femi Babalola Rachel eye center Garki, Abuja.

What is ‘Glaucoma’ A group of diseases. A cause of irreversible blindness. Characterised by three signs: – -Raised intraocular pressure – -Damage to the optic nerve – - Visual field loss.

Glaucoma can be... A. Primary (without an obvious or known cause) B. Secondary (with an attributable cause)

Glaucoma can also be Acute : sudden onset, painful, with wateriness and redness of the eyes. Chronic: gradual, insidious, painless.

Glaucoma can also be characterised as having: Closed angle Open angle

The ‘angle’ of the eye.

Hence the terms: Primary open angle glaucoma. (POAG) Primary closed angle glaucoma (PCAG) Acute angle closure glaucoma Chronic angle closure glaucoma

Commonest type : POAG Primary open angle glaucoma. Known colloquially as the ‘slow thief of sight’. Insidious onset Painless Often discovered during a refraction or other routine exam

Risk factors Age over 40 African descent. Diabetics Hypertension Raised IOP Close relative with glaucoma

The eye as a plumbing system

Blocked drainage : accumulation of fluid (in a closed system this causes elevated IOP

Blocked outflow channel

The ‘angle’ of the eye.

POAG: the angle is open but facility of outflow is reduced.

Narrow angle impairs outflow

Closed angle blocks outflow

The optic nerve: an electric cable connecting the eye to the brain

Raised IOP and nerve damage

Normal optic nerve and retina

Progressive optic nerve damage

Details: nasalisation of vessels, lamina cribrosa, bayonet sign

Optic nerve damage causes visual field loss.

Symptoms resulting: Bumping into objects by the side Seeing ‘rainbows’ around light bulbs. (raised IOL causes ‘water logging’ of the cornea.) Change glasses frequently. (a vain attempt to overcome visual difficulties). Find it difficult to see at night.

A normal eye sees...

A glaucomatous eye sees...

Investigations: slit lamp microscopy

Intraocular pressure: applanation

Non contact Tonometry

Gonioscopy: a study of the angle

Disc photographic analysis and computerised visual field test

Others: nerve fibre layer assessments GDX VCC OPTICAL COHERENCE TOMOGRAPHY (OCT)

Management EARLY DIAGNOSIS IS THE KEY Treatment is targeted at: Lowering intraocular pressure – Medically using eye drops and tablets – Surgically by performing a trabeculectomy, trabeculotomy, canaliculoplasty etc – LASER trabeculoplasty.

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