Q. What is the long-term efficacy of laser trabeculoplasty and medical treatment in PXFG?
A) They both remain highly effective for decades
B) They both lose efficacy after some years
C) Only medical treatment remains effective
D) Only laser trabeculoplasty remains effective
Answer: B) They both lose efficacy after some years
Explanation: Both laser trabeculoplasty and medical treatment are initially effective for managing PXFG, but they tend to lose efficacy after some years. This underscores the need for ongoing monitoring and potential adjustments in treatment strategy.
👁️ Long-Term Efficacy of Laser Trabeculoplasty and Medical Therapy in Pseudoexfoliative Glaucoma (PXFG)
📍 OVERVIEW
Pseudoexfoliative Glaucoma (PXFG) is a secondary open-angle glaucoma caused by deposition of pseudoexfoliative material in the trabecular meshwork (TM), leading to increased outflow resistance and elevated intraocular pressure (IOP).
PXFG is:
- More aggressive than Primary Open-Angle Glaucoma (POAG)
- Associated with higher IOP at diagnosis
- More likely to be unresponsive to monotherapy
- Often requires earlier surgical or laser intervention
⚡ SELECTIVE LASER TRABECULOPLASTY (SLT) IN PXFG
🔬 Mechanism:
- Selective photothermolysis of pigmented TM cells using 532 nm Nd:YAG laser.
- Inflammatory response leads to ECM remodeling and increased aqueous outflow.
📊 Efficacy Data – SLT in PXFG
✅ 1. Martindale et al. (2020, Journal of Glaucoma)
- Study: Retrospective cohort; 71 eyes with PXFG
- Outcome: IOP reduction ≥20% achieved in:
- 73% at 6 months
- 66% at 12 months
- 43% at 24 months
- Median duration of efficacy: 19 months
- Conclusion: SLT is effective in PXFG but with declining long-term efficacy.
✅ 2. Realini et al. (2008, Ophthalmology)
- Study: 5-year follow-up of SLT in PXFG vs POAG
- Results:
- Initial IOP reduction: ~30% in both groups
- Sustained effect longer in PXFG vs POAG
- Findings:
- Greater IOP reduction in PXFG due to high baseline IOP
- Success rate decreased to ~40% by 4–5 years
- Conclusion: SLT is effective in PXFG but requires repeat treatment or adjunctive therapy.
✅ 3. Shazly et al. (2011, Canadian Journal of Ophthalmology)
- Prospective comparative study: PXFG vs POAG
- Result: Greater IOP lowering in PXFG (31%) than in POAG (25%) at 12 months
- Conclusion: SLT may be more effective short-term in PXFG due to TM pigmentation.
🔁 Repeatability
- SLT is repeatable in PXFG, unlike argon laser trabeculoplasty (ALT).
- Efficacy of repeat SLT:
- Second SLT yields lower IOP reduction than the first.
- May provide additional IOP control for 1–2 years.
- No cumulative damage to TM with SLT.
💊 MEDICAL TREATMENT IN PXFG
🚨 Challenges in PXFG:
- Higher and more fluctuating IOPs than POAG
- Faster optic nerve damage
- Worse visual field progression
- Reduced response to monotherapy due to advanced TM obstruction
📊 Efficacy Data – Medical Therapy in PXFG
✅ 1. Konstas et al. (2004, American Journal of Ophthalmology)
- Study: Comparison of latanoprost vs timolol in PXFG and POAG
- Results:
- Latanoprost: ~31% IOP reduction in PXFG
- Timolol: ~23% IOP reduction
- Conclusion: Prostaglandin analogues are most effective single agents in PXFG.
✅ 2. Topouzis et al. (2007, Journal of Glaucoma)
- Longitudinal comparison of PXFG vs POAG with maximal medical therapy
- Findings:
- PXFG required more medications to reach target IOP
- Faster visual field loss in PXFG despite treatment
- Conclusion: Medical therapy less effective long-term in PXFG.
✅ 3. AGIS Study (Advanced Glaucoma Intervention Study)
- PXFG eyes often needed earlier surgical intervention despite maximum medical therapy.
- Visual field progression linked to fluctuating IOP, which is common in PXFG.
💡 TREATMENT COMPARISON: SLT vs MEDICAL THERAPY IN PXFG
| Parameter | SLT | Medical Therapy |
|---|---|---|
| Initial IOP reduction | 25–30% | 20–30% (depends on drug class) |
| Durability | 12–36 months (variable) | Chronic use, but often loses efficacy in PXFG |
| Repeatability | Yes | Not applicable |
| Response in PXFG | Often better than POAG initially | Variable; monotherapy often insufficient |
| Side effects | Minimal | Ocular surface disease, systemic risks |
| Compliance | High (single outpatient session) | Often poor in elderly; multidrug regimens |
| Progression | May delay surgery | Often progresses despite 2–3 medications |
| Cost-effectiveness | High (esp. in resource-limited settings) | Cumulative long-term cost is high |
👁️ TREATMENT OF PXF & PXFG
(Names | Dosages | Mechanisms | Indications | Surgery)
🔹 1. OVERVIEW
- PXF (Pseudoexfoliation Syndrome): Early phase, usually without IOP elevation or optic nerve damage.
- PXFG (Pseudoexfoliative Glaucoma): Later phase with trabecular meshwork obstruction, elevated IOP, and optic nerve damage.
Goals of treatment:
- Lower intraocular pressure (IOP)
- Preserve optic nerve function
- Minimize disease progression
- Improve long-term visual prognosis
💊 2. MEDICAL TREATMENT OPTIONS
PXFG tends to be more resistant to monotherapy than POAG and often requires combination treatment.
✅ A. Prostaglandin Analogues (First-line agents)
| Drug | Dose | Mechanism | IOP ↓ | Notes |
|---|---|---|---|---|
| Latanoprost 0.005% | OD at night | ↑ Uveoscleral outflow | 25–33% | Well tolerated |
| Travoprost 0.004% | OD at night | ↑ Uveoscleral outflow | 25–33% | Good for pigmented irises |
| Bimatoprost 0.01–0.03% | OD at night | ↑ Uveoscleral & TM outflow | 28–33% | Strongest PG analogue |
| Tafluprost 0.0015% | OD at night | ↑ Uveoscleral outflow | 25–30% | Preservative-free; useful in OSD |
📌 Notes:
- Most effective monotherapy
- Minimal systemic side effects
- May cause conjunctival hyperemia, eyelash growth, iris pigmentation
✅ B. Beta-Blockers (Second-line)
| Drug | Dose | Mechanism | IOP ↓ | Contraindications |
|---|---|---|---|---|
| Timolol 0.25–0.5% | BID | ↓ Aqueous production (β1 & β2) | 20–25% | Asthma, bradycardia |
| Betaxolol 0.25% | BID | Selective β1-blocker | 15–20% | Safer for asthmatics, less effective |
📌 Notes:
- Combine well with PG analogues
- Avoid in elderly with cardiac/pulmonary disease
✅ C. Carbonic Anhydrase Inhibitors (Topical)
| Drug | Dose | Mechanism | IOP ↓ | Cautions |
|---|---|---|---|---|
| Dorzolamide 2% | BID–TID | ↓ Bicarbonate production → ↓ Aqueous production | 15–20% | Sulfa allergy |
| Brinzolamide 1% | BID | Similar | 15–20% | Better tolerated (less stinging) |
📌 Notes:
- Often used in combination drops (e.g., Cosopt = Dorzolamide + Timolol)
✅ D. Alpha-2 Adrenergic Agonists
| Drug | Dose | Mechanism | IOP ↓ | Contraindications |
|---|---|---|---|---|
| Brimonidine 0.1–0.2% | BID–TID | ↓ Aqueous + ↑ Uveoscleral outflow | 20–25% | Children <2 y/o, depression, MAOIs |
📌 Notes:
- Neuroprotective potential
- Can cause fatigue, dry mouth, allergy
✅ E. Fixed Combination Therapies
| Brand | Components | Dose |
|---|---|---|
| Xalacom | Latanoprost + Timolol | OD |
| DuoTrav | Travoprost + Timolol | OD |
| Cosopt | Dorzolamide + Timolol | BID |
| Combigan | Brimonidine + Timolol | BID |
| Simbrinza | Brinzolamide + Brimonidine | TID |
📌 Notes:
- Increase compliance
- Reduce preservative exposure
✅ F. Systemic Carbonic Anhydrase Inhibitors (for short-term IOP control)
| Drug | Dose | Indication |
|---|---|---|
| Acetazolamide | 250 mg BID–QID | Acute IOP spikes or pre-op |
| Methazolamide | 50–100 mg BID | Alternative with fewer GI side effects |
⚡ 3. LASER THERAPY
Selective Laser Trabeculoplasty (SLT)
| Parameter | Details |
|---|---|
| Indication | First-line in PXFG or adjunct to drops |
| Mechanism | Stimulates TM remodeling via cytokine release |
| Energy | 0.8–1.1 mJ; 50–100 applications over 360° |
| Effectiveness | 20–30% IOP reduction |
| Duration | 1–3 years; repeatable |
📌 More effective in PXFG than POAG due to heavy TM pigmentation
📌 May delay or reduce need for surgery
🔪 4. SURGICAL OPTIONS
PXFG often progresses to requiring surgery earlier due to poor medication response and IOP fluctuations.
✂️ A. Trabeculectomy (with Mitomycin-C)
| Parameter | Details |
|---|---|
| Mechanism | Creates new fistula for aqueous outflow |
| IOP ↓ | 30–50% |
| Complications | Hypotony, bleb failure, infection, fibrosis |
| Adjunct | Mitomycin-C 0.2–0.4 mg/mL to reduce scarring |
📌 Gold standard for surgical IOP control
📌 More inflammation in PXFG; MMC often required
✂️ B. Glaucoma Drainage Devices (Tubes)
| Type | Indications |
|---|---|
| Ahmed valve, Baerveldt implant | Failed trabeculectomy, scarring, uveitis, neovascular glaucoma |
📌 More predictable IOP control long-term in complex cases
✂️ C. Minimally Invasive Glaucoma Surgery (MIGS)
| Procedure | Device | Notes |
|---|---|---|
| iStent inject | Micro-bypass into Schlemm’s canal | Useful with cataract surgery |
| Hydrus Microstent | Schlemm’s canal scaffold | Combined with phaco |
| XEN Gel Stent | Subconjunctival outflow | Bridge between MIGS and trab |
| GATT (ab interno trabeculotomy) | No implant | Suitable in early PXFG with open angles |
📌 MIGS appropriate for early-moderate PXFG with cataract
👁️ D. Cataract Surgery Considerations
PXF eyes are at increased risk of intraoperative complications due to:
- Zonular weakness
- Poor pupillary dilation
- Capsular instability
Precautions:
- Use capsular tension rings (CTR)
- Iris hooks / Malyugin ring for dilation
- Close post-op IOP monitoring (risk of spikes)
🔄 5. FOLLOW-UP & MONITORING
| Parameter | Frequency |
|---|---|
| IOP (Goldmann tonometry) | Every 3–6 months (more frequent in PXFG) |
| Visual Fields (Humphrey 24-2 or 10-2) | 6–12 months |
| OCT RNFL + Macula | 6–12 months |
| Optic Disc Evaluation | Annually or more |
| Gonioscopy | Annually |
🧠 Summary Table: PXF & PXFG Treatment Overview
| Modality | Options | Mechanism | Notes |
|---|---|---|---|
| Medical | PG analogues, BBs, CAIs, Alpha agonists | ↓ Aqueous, ↑ Outflow | Often need 2–3 agents |
| Laser | SLT | ↑ Trabecular outflow | Repeatable, good early option |
| Surgery | Trab, GDD, MIGS | Diversion of aqueous | Earlier need in PXFG |
| Systemic | Acetazolamide | ↓ Aqueous | For IOP crises |
| Cataract | Phaco + MIGS | Vision & IOP benefit | High zonular risk in PXF |
ROLE OF SURGERY
- Due to poor long-term control with meds/SLT, PXFG often requires:
- Trabeculectomy (with MMC)
- Tube surgery (if prior failure or high risk)
- MIGS + phacoemulsification (in early/moderate cases)
📌 Summary
Due to rapid progression, closer monitoring and earlier surgical referral are recommended.
SLT:
Effective as first-line or adjunctive therapy in PXFG
Better short-term IOP control than in POAG
Efficacy wanes over time; may need repeat treatment
Medical therapy:
Prostaglandin analogues most effective
Often requires polytherapy
Less effective long-term in PXFG due to mechanical TM blockage
Combination of SLT and medical therapy may defer surgery in many cases.