Specifics of Anterior Segment LASER PROCEDURES A.L.T. & S.L.T. ALONE AND IN COMBINATION Leland Carr, O.D. Oklahoma College of Optometry Northeastern State University

Thermal Laser Trabeculoplasty Indications: OPEN ANGLE Glaucomas Must be able to “see” the angle

Trabeculoplasty is appropriate for: Primary Open-angle glaucoma Pigmentary Glaucoma Pseudoexfoliative Glaucoma Normal Tension Glaucoma Angle-recession Glaucoma

Trabeculoplasty may be appropriate for ANGLE RECESSION GLAUCOMA A.L.T. –Apply treatment to NON-recessed angle S.L.T. –Apply treatment to NON-recessed angle

NSU-OCO Study Apply SLT to 360-degrees following Angle Recession---prior to development of ANGLE CLOSURE GLAUCOMA ?????

Trabeculoplasty is NOT appropriate for: Primary Closed-angle Glaucomas Secondary Closed-angle Glaucomas Inflammatory Glaucomas Neovascular Glaucomas

S.L.T. may be appropriate in the management of Primary Angle Closure Glaucoma Southeast Asian Study (6 centers) 50 patients Chronic Angle Closure Glaucoma (“combined mechanism glaucoma”) Dual Laser Therapy –Peripheral Iridotomy –S.L.T.

Mechanism(s) of action Mechanical Effects Photobiostimulatory Effects

Laser//Tissue Interaction A.L.T. –“thermal process” –MECHANICAL EFFECT –Laser energy converted to heat following absorption by melanin –Significant peripheral heat-spread S.L.T. –“non thermal” –BIOSTIMULATORY EFFECT –Energy delivery is small and brief Only 1% the effective energy associated with A.L.T. –Energy absorbed very locally by melanin containing cells –No heat build-up to thermal relaxation time of melanin

A.L.T.’s impact on meshwork

S.L.T.’s impact on meshwork

Anecdotal Reports: “A.L.T. doesn’t work as well on pseudophakes as it does on phakic patients.” “S.L.T. seems to work equally well on phakic, aphakic, and pseudophakic patients.”

A.L.T. Performing Argon Laser Trabeculoplasy

Perform Gonioscopy Obtain Informed Consent Instill 1 gt. Iopidine or 1 gt. Alphagan-P (rarely) Instill 1 gt. 1-2% Pilocarpine

Performance of A.L.T. Treat 180 or 360 degrees? 50 – micron spot (argon) Approximately 60 burns per 180 degrees Apply to anterior ½ of meshwork

Obtain “blanching” to whitening of tissue (adjust Power setting to obtain it) – Avoid “charcoaling” – Avoid “bubbling” – Avoid “blistering”

Or……Just make it easy! Set power at 1000 mWatts

Post-op Instill 1 gt Iopidine or 1 gt Alphagan-P Rx: PredForte 1 gt. q.i.d. Rx: Continue all pretreatment glaucoma medications –Including Prostamides! –If not currently using Mx, go with Alphagan-P 1 gt t.i.d.  Recheck patient at 1 week

Most often do LOWER angle first Most often do NOT retreat upon previously-treated meshwork! –60% will benefit in terms of new IOP lowering –40% will NOT benefit, and will often respond with a rise in IOP

Be Patient……. Need to wait for 4-6 weeks to assess efficacy of A.L.T.

Followup Continue ALL pre – treatment glaucoma medications, but consider tapering if ALT results warrant Use Pred – forte to control iritis, only as needed Avoid judging the effects for 4 – 6 weeks Recheck adequacy of control each 3 months – Especially likely to “drift” first two years

S.L.T. Selective (wavelength) Laser Trabculoplasty For Open Angle Forms of Glaucoma

S.L.T. Basics Q-switched, Frequency-doubled Nd:YAG Laser System –Outputs 532 nm emission –Brief 3 nsec pulse –“Low Power” (Energy) burns Targets Pigmented Trabecular Meshwork Cells Minimal “peripheral damage” to non- pigmented cells and/or collagen

Laser Trabeculoplasties; SPOT SIZES ARGON procedures:50 microns DIODE procedures:60 microns S.L.T. procedures :400 microns

How is it working? “Gentle mechanical effect” (minor) –Reshaping meshwork anatomy and mechanics –Less dramatic than the A.L.T. effect “Biostimulatory effect” (major) –Increased cellular metabolism –Increased cellular mitosis

“Enhanced Housekeeping” Stimulate macrophages Release cytokines Remove metalloproteases

S.L.T. Performing Selective Wavelength Laser Trabeculoplasy

Discontinue all glaucoma medications 1-2 weeks prior to S.L.T. (?????) Ellex SLT website Mrs. Madhu Nagar “I prefer to discontinue all glaucoma medications prior to SLT, rather than post SLT. The higher the baseline IOP, the greater the IOP reduction.”

Perform Gonioscopy Obtain Informed Consent Instill 1 gt. Iopidine or 1 gt. Alphagan-P (rarely) Instill 1 gt. 1-2% Pilocarpine

S.L.T. Treatment Parameters Wavelength: 532 nm Pulse:3 nsec Spot:400 microns Energy per pulse:.6 to 1.2 mJoules Shots:45-55 “adjacent” Location:inferior or nasal 180-degrees

Laser Lens Goldman 3-Mirror A.L.T. Trabeculoplasty Lens Better to NOT use a Diode Trabeculoplasty Lens

Titrate the Energy Setting Start with around.6 mJoules Gradually increase setting to produce a visible “steam” of micro- bubbles upon firing the laser (viewed through the slit-lamp and laser lens)

Or……Just make it easy! Set energy at 1.0mJ

Best to Avoid the 11:00 – 1:00 Zone? Better to leave the meshwork “virgin” in the area where a filtering procedure might need to enter the angle? Also Consider: The Advanced Glaucoma Intervention Study indicated that African-American patients have better surgical outcomes when A.L.T. is done prior to a filtering procedure

Treat 180 or Treat 360 Degrees 180 advocates –Less risk of a laser-induced IOP spike –(Perhaps) advisable for Pigmentary and Pseudoexfoliative Glaucoma patients 360 advocates –(Perhaps) greater IOP reduction –(Perhaps) longer duration of efficacy

Post-Procedure Don’t use steroids unless an intense iritis occurs –Expect to see pigment immediately post-op Use Topical and Systemic Non-Steroidals –Acular, Nevanac, Voltaren (1 drop 4-5 times daily) –Ibuprofen (two 200mg tables 4 x daily) –Treat for 3-4 days

Don’t try to judge the efficacy for at least a month, and 6-8 weeks is really a better time for assessment of treatment success

OUTCOMES Expect all patients will require at LEAST two separate treatments to produce a maximal effect! Best to wait at least 6 weeks before doing the second (and subsequent) treatments Works on over 70% of treated eyes Expect a 22% to 28% reduction from pre-treatment IOP

When to retreat/repeat SLT? As soon as pressure starts rising again. No harm done by waiting until IOP surpasses target IOP…..but why wait?

Medicare Exclusion: 10 Days And you really want to wait for at least 6 weeks prior to a retreatment, anyway!

Outcomes Most often effects last a least one year Average SLT “usefulness” is 3 years Do expect some loss of efficacy over time S.L.T. is repeatable S.L.T. can be safely performed on patients who have previously had Argon or Diode trabeculoplasties

COMBINATION ALT/SLT Perform standard A.L.T. As “drift” becomes apparent, re-treat the meshwork using S.L.T. Some experts consider that A.L.T. pressure-lowering can be enhanced using immediate S.L.T. follow-up treatments –Maximal mechanical impact –Maximal biostimulatory impact

S.L.T. can be tried on “failed” A.L.T. cases Studies have shown that up to 80% of “A.L.T. failures” can be successfully treated with S.L.T. Typical IOP reduction is approximately 22% from pre-S.L.T. baseline