7. Treatment

Treatment Aims

• Preserve visual function (acuity and fields)

• Preserve the eye (minimise pain)

• By reducing intraocular pressure (IOP) to an acceptable level and maintaining it over time

Medical Management Overview

• Target IOP depends on optic nerve head (ONH) damage and field loss

• On POAG diagnosis, aim to reduce IOP by 1/3 of baseline

• Start as monotherapy (fellow eye used as control) and review in 2 weeks (2/52)

• If sufficient drop in IOP, commence treatment in fellow eye

• If insufficient drop, options include:

  • Substitute drug

  • Add another drug (multi-drug therapy or fixed combinations)

• Continual monitoring of IOP and visual field (VF)

• Failure criteria:

  • Insufficient lowering of IOP

  • IOP lowered but VF loss progresses

  • Non-compliance, side effects, cost, or other factors

Medications Available in Australia (Table 9.1: Medications in glaucoma management)

• Summary of usage sequence (from table):

  • FIRST: Prostaglandin analogues; Beta-blockers; alpha2-agonists; fixed combinations may be used

  • SECOND: Add topical CAIs or alpha2-agonists as needed; consider combinations

  • THIRD: Add or switch to systemic CAI (acetazolamide) or cholinergics if needed

Medications: Contraindications, Precautions, and Interactions (Table 9.3)

Surgical and Laser Management: When Medical Therapy Isn’t Enough

• When maximum medical therapy (MMT) fails or is no longer tolerated:

• Open the angle

  • Cataract extraction (Cat & IOL)

• Increase/promote outflow through an existing pathway

  • Peripheral iridotomy/iridectomy (PI)

  • Argon/Selective Laser Trabeculoplasty (ALT/SLT)

  • Goniotomy

• Create a new outflow pathway

  • Filtration surgery (Trabeculectomy)

  • Drainage device (Molteno tube)

• Turn off the tap

  • Cyclodestructive procedures (Trans-scleral laser cyclodiode)

Cataract Surgery and IOL in Glaucoma Care

• Cataract extraction with IOL can:

  • Increase anterior chamber depth

  • Widen the anterior chamber angle

• Evidence on cataract removal in glaucoma management is mixed; some controversy remains regarding outcomes in certain glaucoma patients

Peripheral Iridotomy vs Peripheral Iridectomy

• Peripheral Iridotomy (PI) with YAG laser

  • Indications: Primary angle closure; narrow occludable angles

  • Technique: Performed under upper eyelid to minimize glare/monocular diplopia; post-op topical steroid for ~1 week

• Peripheral Iridectomy

  • Indications: Primary angle closure with pupil block

  • Function: Creates a broader pathway for aqueous to enter the anterior chamber

Laser and MIGS Options

• A/SLT (Argon/Selective Laser Trabeculoplasty)

  • Mechanism: Create discrete burns to trabecular meshwork to enhance outflow

  • Efficacy: Modest IOP reduction; typically less than 30%;

  • Often not sufficient as a standalone treatment and may require ongoing medical therapy

  • useful for non-compliance

• Goniotomy

  • Indication: Developmental glaucoma with abnormal drainage network

  • Mechanism: Sweep incision through trabecular meshwork to improve outflow

  • Potential long-term complications: Corneal decompensation in some cases

• Trabeculectomy (trab)

  • Filtering/drainage surgery

  • MMT and A/SLT failure

  • Creates a new pathway for aqueous outflow from AC to sub-tenon’s space

  • Significant (typically long term) IOP reduction

  • Antimetabolites to reduce scarring
    
    

  

• Artificial Drainage shunts

  • plastic tube which creates a pathway from the AC to sub-Tenon’s space

  • Failed trabeculectomy or trab not possible

  • Potential for complications high:

    • Excessive drainage -> collapsed AC

    • Tube blockage (blood, iris) -> IOP

    • Exit bleb seals -> IOP

    • Tube erosion through conjunctiva

• MIGS (Minimally Invasive Glaucoma Surgery)

  • Stent-based approaches to increase outflow, designed to be less invasive

  • For patients undergoing cataract surgery

  • Goals: Reduce medication burden or achieve medication-free control in suitable patients

  • Not intended for malignant glaucoma or patients on maximum medical therapy (MMT)

• I-Stent (Australia)

  • Status: The only device currently approved in Australia (as per provided material)

  • Design: ~1 mm stent implanted in Schlemm’s canal; typically placed into a nearby collector vessel around 9 o’clock position in the eye canal

• Cyclodiode:

  • Lower IOP by reduction of aqueous production (ablation of the ciliary body processes epithelium)

  • Uncontrollable with MMT or surgery

  • Often end stage glaucoma

  • Pain relief, save the eye (even if blind)

  • Major complications (pthisis/hypotony

  • last line of defence