POAG

Dr.Syeda Fahmida Farzana Aziz

Introduction

Definition:Primary open-angle glaucoma (POAG) is a commonly disease of adultonset.

It is characterized by:

• IOP >21 mmHg at some stage.• Glaucomatous optic nerve damage.• An open anterior chamber angle.

Introduction Cont..

• Characteristic visual field loss as damage progresses.• Absence of signs of secondary glaucoma or a non-

glaucomatous cause for the optic neuropathy.

Risk factors

• The higher the IOP, the greater the likelihood of glaucoma.• POAG is more common in older individuals.• More common in black individuals.• Family history of POAG• Diabetes mellitus• Myopia

Risk factors Cont..

• Contraceptive pill. • Vascular disease. • Translaminar pressure gradient.• Large discs may be more vulnerable to damage• Ocular perfusion pressure

Pathogenesis of glaucomatous optic neuropathy

• Direct mechanical damagedamage to retinal nerve fibres at theoptic nerve head, perhaps as they pass through the laminaCribrosa.• Ischaemic damagedue to compression of bloodvessels supplying the optic nerve head.

Changes in glaucoma

(a) the optic nerve head (b) the peripapillary area and (c) the retinal nerve fibre layer

Subtypes of glaucomatous damage

• Focal ischaemic discs• Myopic disc with glaucoma• Sclerotic discs• Concentrically enlarging discs

Non-specific signs of glaucomatous damage

• Disc haemorrhages• Baring of circumlinear blood vessels• Bayoneting• Collaterals between two veins• Loss of nasal NRR• The laminar dot sign• ‘Sharpened edge’ or ‘sharpened rim’

Optic Disc findings

Steroid responsiveness

Elevation of IOP in response to a course of steroid is more marked in patients with POAG and their close relatives.

Screening

Routine screening eye examinations• Visual field assessment• Tonometry• Ophthalmoscopy

Investigation

• Pachymetry for CCT.• Perimetry • Imaging of the optic disc, peripapillary RNFL and/or ganglion cell complex, e.g.–Red-free photography,– Stereo disc photography,

Investigation Cont..

–OCT,–Confocal scanning laser ophthalmoscopy– Scanning laser polarimetry.

Treatment goals

1. Target pressure: IOP level is identified below which further damage is considered unlikely.

2. Proportional reduction in IOP by a certain percentage – often 30%

and then monitor, aiming for a further reduction if progression occurs.

3.Response to progression.

Treatment goals

Target IOP depend upon• IOP at which damage has occurred.• Severity of visual field damage.• Rate of progression of damage.• Age and Life expectancy.

Management

The primary aim of treatment is to prevent functional impairment of vision within the patient’s lifetime by slowing the rate of ganglion cell loss.

Currently the only proven method of achieving this is the

lowering of IOP.

Management Medical - Antiglaucoma drugs

LASER – SLT, ALT, MLT

Surgical

Types of medications

Beta blockers Alpha-2 agonists Prostaglandin analogues

CAIs Miotics Hyperosmotic agents

Medical therapy

• 1. Commencing medical therapy Initial treatment is usually with one drug in its lowest

concentration with the desired therapeutic effect & fewest potential side effects .

2.Review:• Response to the drug is assessed against the target IOP.• If the response is satisfactory subsequent assessment is

generally done for a further 3-4 months.

Medical therapy(contd)

• If there has been little or no response the initial drug is withdrawn and another substituted.

• If there has been an apparently incomplete response another drug may be added or a fixed combination substituted.

• When two separate drugs are used the patient should be instructed to wait five minutes before instilling the second drug to prevent washout of the first.

Medical therapy(contd)

3. If IOP control is good and glaucomatous damage mild or moderate with no substantial threat to central vision, annual perimetry is generally sufficient.4. Gonioscopy should be performed annually because anterior chamber angle tends to narrow with age.5. Optic disc examination

Surgical treatment

• Trabeculectomy is the surgical procedure most commonly performed for POAG.• Phacoemulsification alone is frequently associated with a significant fall in IOP, but is generally only offered to patients in

whom significant lens opacity is present.

Surgical treatment cont..

Indications Of Surgery 1. Progressive deterioration despite maximum medical therapy2. Avoidance of excessive polypharmacy and drug intolerance3. Primary therapy- advanced disease requiring very low target

pressure4. Patient preference

Laser Treatment

Indication of Laser trabeculoplasty• Intolerance to topical medication• Failure of medical therapy• Avoidance of polypharmacy• Avoidance of Surgery• Primary therapy

Patient counselling

Full informations regarding the disease Informations regarding the medications. Mode of administering the drug. Informations regarding expected side effects

Prognosis

• The great majority of patients diagnosed with POAG will not be blind in their lifetime but the incidence of blindness varies considerably.

• Bad prognostic factors are: Advance damage at diagnosis Non-compliance with treatment Ethnic origin-black patients.

Take home message

Glaucoma is the second leading cause of blindness . Glaucoma is a treatable disease, if detected earlier & treated

properly we can stop the progression of glaucomatous damage.

By making good awareness about glaucoma we can minimize family, socio-economic & as a whole national

burden.