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LASER THERAPY IN GLAUCOMA. Sun Xiao Dong. Laser Procedures. Laser trabeculoplasty(LTP) Laser peripheral iridotomy(LPI) Cyclophotocoagulation(CPC) Other uses. Laser Trabeculoplasty(LTP).
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LASER THERAPY IN GLAUCOMA Sun Xiao Dong
Laser Procedures • Laser trabeculoplasty(LTP) • Laser peripheral iridotomy(LPI) • Cyclophotocoagulation(CPC) • Other uses
Laser Trabeculoplasty(LTP) • Apply multiple laser burns to the trabecular meshwork to improve aqueous outflow • Lasers Argon(ALT) Nd:YAG(SLT)
Indications for LTP Supplement to maximum tolerated medical therapy Poor compliance Initial therapy(GLT)
Contraindications: 1.Corneal edema 2.Complete angle closure glaucoma 3.Age﹤35 years 4.Some secondary open angle glaucomas(eg uveitic glaucoma,angle recession glaucoma) Relative contraindication Laser Trabeculoplasty(LTP)
ALT Preoperative treatment: 1 drop of lopidine 1hour before treatment Postoperative treatment: 1.1 drop of lopidine immediately after treatment 2.Iop check 1-3 hours after treatment and first postlaser day 3. Pres Forte 1% qid for 4 days 4.Evaluate effect in 4-6 weeks
ALT Laser technique: 1.Goldmann 3-mirror or 1-mirror lens 2.Argon laser settings: 300-1200mW(average 800mW) 50 μm 0.1sec 3.50 burns over 180°or100 burns over 360°applied to junction of pigmented and nonpigmented TM
ALT • Complications: 1. Elevation of IOP 2. Progression of visual field 3. Iritis 4. Peripheral anterior synechiae 5. Corneal epithelial and endothelial damage
ALT 1.Short-term results initial success: 65-95% Reduction in IOP: 20-30% 2.Long-term results Attrition rate: 5-10% per year 5 year succes rate: 50%
ALT Factors influencing response: 1.Pre-treatment IOP 2.Aphakia/pseudophakia 3.Age 4.Race 5.Type of glaucoma
Laser Trabeculoplasty Pathophysiology: 1. Shrinkage of collagen in TM which pulls open the intertrabecular spaces between treatment sites(Wise &Witter) 2. Stimulates trabecular endothelial cells to divide and migrate(Acott) 3. Stimulates trabecular endothelial cells to produce an altered extracellular matrix that is less outflow-obstructing(VanBuskirk)
Laser Peripheral Iridotomy(LPI) Create a hole in the iris to relieve pupillary block Lasers Argon Nd:YAG
LPI Indications: 1. Acute ACG 2. Chronic ACG 3. Aphakic/pseudophakic pupillary block 4. Partial thickness surgical iridectomy 5. Before laser trabeculoplasty in eyes with narrow angles 6. Pigment dispersion syndrome/pigmentary glaucoma
LPI Indications: Prophylactic laser iridotomy 1.Acute ACG in other eye 2.Symptoms of subacute ACG 3.Appositional closure 4.PAS 5.↑IOP and closure of angle with dilation 6.Inability to be evaluated promptly 7.Patient anxiety regarding risk of ACG
LPI • Contraindications: 1.Significant corneal edema 2.Flat AC 3.Completely closed angle 4.Angle closure glaucoma not caused by pupillary block
LPI Preoperative treatment: 1 drop of lopidine and pilocarpine 1 hour before treatment Postoperative treatment: 1. 1 drop of lopidine immediately after treatment 2. IOP check 1-2 hours after treatment 3. Pred Forte 1% qid for 1 week
LPI Laser technique: 1.Abraham or Wise lens 2.Laser settings: Argon: 700-1500mW 50μm 0.02-0.1 sec Nd:YAG: 3-7mJ 1-3shots/pulse
LPI Laser technique: 1.Select site at 12:00 in base of a peripheral iris crypt 2.Endpoint: Pigment epithelium storm Lens capsule visualized Clear iris transillumination
LPI • Complications: Hyphema Iritis Increased IOP Corneal epithelial and endothelial burns Lens opacities Pupillary distortion Monocular diplopia and glare Closure of iridotomy
Cyclophotocoagulation(CPC) Destroy cilary body to reduce the rate of aqueous production Lasers Diode Nd:YAG
CPC Indications: 1.Pain caused by high IOP in eye with little or no visual potential 2.Unable to undergo filtering surgery for medical reasons 3.Failed piror filtering surgery and/or at high risk of failure for repeat filtering surgery
CPC Preoperative treatment: Retrobulbar anesthesia Postoperative treatment: 1. Patch for 24 hrs 2.Atropine 1% bid and Pred Forte 1% q 2 hrs WA gradually tapered over several weeks 3. Resume glaucoma medications except miotics
CPC Postoperative treatment: Narcotic analgesic prn pain Retreatment if needed about 1 month after initial procedure
CPC Laser technique: Noncontact,slit lamp system or contact probe,fiberoptic system Nd:YAG laser settings: 4-8J 30-40 burns over 360°about 1 mm posterior to limbus
CPC Laser technique: Diode laser settings: 1-2W 2.0 sec 18 burns over 270°about 1 mm posterior to limbus
CPC Complication: Iritis Pain Conjunctival burns Visual loss Phthisis bulbi Hypotony Cystoid macular edema
CPC Complications: Corneal graft rejection Hyphema Vitreous hemorrhage Cataract Suprachoroidal hemorrhage Serous choroidal effusion Sympathetic ophthalmia
Other uses of Laser Therapy Laser suture lysis 1.Use laser to cut sutures in the trabeculectomy flap to improve filtration in the early postoperative period 2.Laser technique Hoskins or Ritch lens Argon laser settings: 300-800 mW 50 μm 0.02-0.1sec
Other uses of Laser Therapy Laser peripheral iridoplasty 1.Use laser to create contradiction burns in the peripheral iris to open an appositionally closed angle (eg plateau iris syndrome,nanophthalmos) 2.Laser technique: Abraham or Goldmann lens Argon laser settings: 150-300mW 500μm 0.2-0.5sec