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Glaucoma Laser Surgery: SLT, ALT, ECP

Glaucoma Laser Surgery: SLT, ALT, ECP. Thomas E. Stickel, OD FAAO The Eye Center, Inc. Florissant, MO 63031. Learning Objectives – Part I. Describe differences between Selective Laser Trabeculoplasty and Argon Laser Trabeculoplasty Compare efficacy of SLT and ALT

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Glaucoma Laser Surgery: SLT, ALT, ECP

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  1. Glaucoma Laser Surgery: SLT, ALT, ECP Thomas E. Stickel, OD FAAO The Eye Center, Inc. Florissant, MO 63031

  2. Learning Objectives – Part I • Describe differences between Selective Laser Trabeculoplasty and Argon Laser Trabeculoplasty • Compare efficacy of SLT and ALT • Learn pros and cons of LT and who makes a good patient

  3. Laser Trabeculoplasty (LT) • Comes in two flavors • Argon Laser Trabeculoplasty • Selective Laser Trabeculoplasty • Not to be confused with Trabeculectomy (glaucoma filtration surgery; a “filter”) • -plasty is “molding or forming surgically” • -ectomy is “the cutting out of something” • -otomy is “the act of cutting, incision”

  4. Laser Trabeculoplasty • Low energy laser exposures to the TM • ALT – Heat to TM causes physical damage • SLT – Selectively targets melanin in TM – very little heat/physical damage • Most common type of glaucoma surgery done • Treatment for Open Angle Glaucoma (OAG) • Usually an adjunctive therapy along with one or two topical meds, but can be done first line

  5. Laser Trabeculoplasty • ALT/SLT is used now if: • Maximum medical therapy cannot control IOP but glaucoma not severe • Patient is uncompliant, unable, or just wants to decrease topical meds • Efficacy varies with the type of glaucoma

  6. Laser Trabeculoplasty • Expect a 3-8 mmHg drop in IOP or a 20 percent IOP reduction with either procedure • ALT “controls” IOP in 80 percent of eyes at one year, 50 percent at 5 years, and 30 percent at 10 years • ALT may be repeated once, but repeat not as efficacious • SLT “control” of IOP not as well studied but appears to lose little efficacy over five years • SLT is repeatable

  7. SLT vs. ALT • SLT has been shown on average to have equal efficacy to ALT • Juzych et al 2004 • Equal IOP lowering over 5 years • Suggests loss of effect in SLT? • Damji et al 2006 – equal effect over 1 year • Barkana et al 2007 • Stein et al 2007

  8. Mechanism of Action - ALT • Increased aqueous outflow • In ALT, thermal shrinkage of the collagen sheets at the site of the laser burn pulls open the adjacent area next to the burns, opening up Schlemm’s canal • Besides mechanical there is also a cellullar response

  9. Mechanism of Action - SLT • The Cellular theory suggests that trabecu-loplasty stimulates cells in the TM to produce cytokines • Cytokines cause monocyte recruitment, leading to division, migration, and metabolic activity of macrophages

  10. Mechanism of Action - SLT • This macrophage activity “cleans up” TM to increase outflow • SLT supports this theory because SLT is not “hot” enough to cause mechanical changes

  11. SLT

  12. SLT

  13. Advantages of SLT versus ALT • Less damage to TM • Fewer side effects • IOP Spike • Peripheral Anterior Synechiae • IOP lowering effect is similar, however SLT appears to last longer • Repeatable even in eyes with previous ALT (Hong 2009, Birt 2007)

  14. Repeatability of SLT after ALT • Birt 2007 CJO compared: • SLT after 360 of ALT • SLT as first line Tx • ALT as first line Tx • No statistically significant differences at one year F/U • All three groups had IOP reduction of 19.3-24% • Small decrease in meds used in both SLT groups

  15. Case History #1 - DS • 64 yoWM, S/P cataract surgery OU, presents with: • Normal VA • Increased IOP: OD: 25 OS: 15 • No history of trauma to OD • No history of increased IOP in past • Brother with COAG • Borderline VF/imaging OD, normal OS

  16. Case History #1 - DS • Options: • Xalatan tried first – IOP reduced to OD: 16 (36%) • Counseled on SLT – IOP reduced to OD: 17 without Xalatan

  17. Case History #1 - DS • Advantages of SLT over topical TX • (Relatively) young glaucoma patient – may be putting on Xalatan for 30 years • Unilateral • patient only has one set of SLT visits • Topical Tx in one eye 95% as much hassle as in two – one laser gets rid of hassle • No unilateral raccoon eye/lash growth/iris change

  18. SLT vs. ALT treatment • Uses a Q switched frequency doubled nd:YAG laser • Shorter pulse of energy: 3ns • Larger beam diameter: 400um • Exposure time is less • YAG laser is not thermal, Argon is

  19. SLT vs. ALT • The melanin pigment is primarily affected • Affects only pigmented trabeculum • This allows for equal effect with fewer side effects • Less scarring/ collateral damage • Greater biological and chemical effect

  20. Laser Damage to TM ALT SLT

  21. SLT Studies • No major NIH funded study of SLT • Still good effect at 5 year mark (Lai 2004; Weinand 2006) • Equal efficacy with ALT, from 3-8 mm reduction, or 18-40% (Melamed 2003; Damji 2006; Barkana 2007; Stein 2007)

  22. SLT Studies • Statistically equal to latanoprost as first line treatment (Nagar 2005, McIlraith 2006). • Non-responder rate varies from 4% to 41% (Melamed 2003; Nagar 2005; Barkana 2007) depending on criteria

  23. ALT Studies • A number of studies were done to determine if ALT should be the first line treatment for glaucoma • Glaucoma Laser Trial (1990) • One eye treated with medical the other ALT • Found that ALT • Better controlled IOP and Visual Field Loss • Compared to Timolol (no Xalatan at that time) • Glaucoma Laser Trial Followup (1995) • 3-5 years later • Reduction in IOP’s about the same • Laser eyes showed slightly improved VF • Found that ALT was as efficacious as Timolol • AGIS Study • Found long term these patients did well with both VF and IOP

  24. ALT/SLT works better in some types of glaucoma • Good • Pseudoexfoliation syndrome • Pigmentary Glaucoma • POAG • Bad • Low tension • Aphakia or pseudophakia (?) • Neovascular • ICE syndrome • Sturge-Weber Syndrome • CACG (treat visible areas) • Ugly • Congenital • Juvenile • Steroid induced • Angle recession/ traumatic • Uveitic/ inflammatory

  25. Does cataract surgery matter? • It’s been theorized that cataract surgery causes a cellular response similar to SLT • Patients have IOP reduction after cataract surgery • Is it due to a cellular effect? • Is it due to phyical opening of the TM?

  26. Does cataract surgery matter? • Two studies show that SLT works equally well in phakic and pseudophakic eyes • Werner et al 2007 IOP reduction of 2.6 for phakic and 2.9 for pseudophakes • Mahdaviani et al 2006 show 78% of pseudophakic and 80% of phakic eyes have >3 IOP reduction at 1 year.

  27. What’s good for one eye… • Rhodes 2009 showed a statistically significant IOP reduction in the contralateral eye of 50% • Average of 3.9 ipsilateral / 2.1 contralateral • Supports cellular mechanism

  28. Pros… • Laser treatment is easy and you can do it if you work in a laser state • SLT can be repeated because no scarring or damage to trabecular meshwork • Patients appreciate not having daily hassle of drops, monthly hassle of refilling prescriptions, and the constant drain of copays

  29. …and Cons • It’s surgery – there can be complications • It’s surgery – you probably won’t be doing it • Some patients prefer medical because of fear of surgery • Low but definite non-response rate • Lots of follow up

  30. Coding • Procedure code 65855 RT/LT (SLT/ALT) • Includes 10 day global period • You may not charge for any routine post-op care within 10 days of procedure • Pre-op exam • 92004/92014 (new/est. comprehensive) • 92015 (refraction) • 92020 (gonioscopy)

  31. Coding • Can do procedure on same day as exam • Need -25 modifier – separate, identifiable E/M service on same day as surgery or other service

  32. Case History #2: MS • 91 yo WF with long history of OAG • Currently taking Xalatan qhs OU • Highest untreated IOP 24/26 • Currently 14/16 on Xalatan • 0.5 cups OU with early VF damage

  33. Case History #2: MS • Plan: SLT OU with target pressure <18 • SLT performed OU, pressures stable between 15-18 OU with no VF progression

  34. Case History #2: MS • Target IOP: Don’t go too low • Patient didn’t need 50% reduction from Xalatan • Doesn’t need aggressive Tx given life expectancy • Older patients • Often on fixed income • Difficulty with drops - arthritis • Polypharmacy

  35. Take 5

  36. Learning Objectives – Part II • Contraindications/Complications of LT • Learn details of pre-op and post-op as well as LT itself • Become familiar with Endoscopic Cyclophotocoagulation (ECP)

  37. Contraindications • Inadequate visualization of the trabecular meshwork • Narrow Angle • Corneal edema or opacities • View of angle and absorption of laser • Extensive peripheral anterior synechiae (PAS), iris processes or iritis/uveitis • Laser iridoplasty should be performed first to attempt to break PAS • Un-cooperative patients • Unable to sit at slit lamp

  38. Relative Contraindications • Treatment is relatively ineffective • Congenital glaucoma • Juvenile glaucoma • Steroid induced • Essential atrophy • Marfan syndrome glaucoma

  39. Laser Instrumentation • Argon laser is used for ALT • Nd:YAG laser used for SLT • Other lasers • Krypton laser • Diode laser • Copper Vapor Laser

  40. Contact Lens • Lens allows views of the angle structures to direct laser to trabeculum • Lens magnifies view • Lens concentrates the laser energy to the target trabeculum • Lens acts as a speculum and controls eye movement • Minimizes energy density on the retina by diverging the laser beam • Numerous types of lenses • Goldmann three mirror most common for ALT • Latina most common for SLT – essentially a three mirror with one mirror

  41. Pre-Op Exam • Case history • Glaucoma history, previous procedures and existing ocular pathology: Uveitis, trauma • Current number of meds – overtreated already? On meds that have never been shown to work? • VA Testing • Manifest refraction • Applanation tonometry

  42. Pre-Op Exam • Slit lamp exam • Cornea • Guttata, Krukenberg’s spindle. • Anterior chamber • Iritis, shallow a/c • Iris • Rubeosis, PEX, iridotomy, iris atrophy • Lens • PEX, Pigment Dispersion

  43. Pre-op Exam • Gonioscopy • Structures: Trabecular meshwork visible? • Pigment in angle, PAS, Rubeosis • Angle recession • BIO + direct/78/90 • Pachymetry – better able to set target IOP • Threshold Perimetry and/or structural imaging • Informed Consent – indications, alternatives, risks, benefits

  44. Pretreatment Regimen • Continue glaucoma medications that day • 1% apraclonidine (Iopidine) • Prevent IOP spike • Proparacaine • Some doctors use pilocarpine: better view • Advise patient about noises and flashes • Ensure head stabilization and minimal eye movement • Adjust focus: Oculars and alignment of laser, fixation target.

  45. Treatment Procedure • 25X Magnification • Examine the entire angle 360 degrees before surgery • Ensure identification of angle structures • ICan’t See That Stupid Line • Identify areas of PAS or blood vessels and avoid during treatment • Move fixation light in direction of the mirror • For example when viewing inferior angle with superior mirror move the fixation light up

  46. Argon Laser Parameters • Spot Size • 50 um spot size • Duration • 0.1 second duration • Power/ Energy • 800 to 1200mW power level. • Can increase power levels in 100mW steps until small bubble formation or blanching of the trabecular meshwork • Increased power increases risk for PAS • Vary levels of energy based upon pigmentation • Lower levels for increased pigmentation because more absorption • i.e. Pigment dispersion syndrome • Wavelength • Blue-green

  47. SLT Laser Parameters • Frequency doubled to 532 nm light • Spot Size • 400 mm spot size • Duration • 3 nanosecond duration • Power/ Energy • 0.6 mJ to 1.2 mJ • Can increase power levels until “champagne bubble response” • Vary levels of energy based upon pigmentation • Lower levels for increased pigmentation because more absorption

  48. Placement of burns with ALT vs. SLT • For ALT, place burns anteriorly in the trabecular meshwork (TM) at or near the junction of the pigmented and non-pigmented meshwork. • If no pigment place in the middle of the TM • For SLT, cover TM

  49. ALT Laser Burn Application • Treat 180 degree of angle with 40-50 evenly spaced burns • Some doctors treat 360 at one sitting • Others may only treat 90 • Look for blanching of the trabecular meshwork or small bubble formation • If no effect or the effect diminishes with time: treat other half of angle • Some studies indicate treating half the angle is just as efficacious as treating 360 • Treating 180 results in fewer side effects • IOP spikes • PAS

  50. SLT Laser Burn Application • Treat 360 degree of angle with 100 evenly spaced burns • Prasad 2009 showed 35% reduction with 360 vs. 28% for 180 • 180 degree group had more fluctuation in IOP throughout first two years • Look for champagne bubble response

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