Specifics of Anterior Segment LASER PROCEDURES A.L.T. - PowerPoint PPT Presentation

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Specifics of Anterior Segment LASER PROCEDURES A.L.T.

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Title: Specifics of Anterior Segment LASER PROCEDURES A.L.T.


1
Specifics of Anterior Segment LASER
PROCEDURESA.L.T. S.L.T.ALONE AND IN
COMBINATION
  • Leland Carr, O.D.
  • Oklahoma College of Optometry
  • Northeastern State University
  • CarrLW_at_nsuok.edu

2
Thermal Laser Trabeculoplasty
  • Indications OPEN ANGLE Glaucomas
  • Must be able to see the angle

3
Trabeculoplasty is appropriate for
  • Primary Open-angle glaucoma
  • Pigmentary Glaucoma
  • Pseudoexfoliative Glaucoma
  • Normal Tension Glaucoma
  • Angle-recession Glaucoma

4
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

5
NSU-OCO Study
  • Apply SLT to 360-degrees following Angle
    Recession---prior to development of ANGLE CLOSURE
    GLAUCOMA ?????

6
Trabeculoplasty is NOT appropriate for
  • Primary Closed-angle Glaucomas
  • Secondary Closed-angle Glaucomas
  • Inflammatory Glaucomas
  • Neovascular Glaucomas

7
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.

8
Mechanism(s) of action
  • Mechanical Effects
  • Photobiostimulatory Effects

9
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

10
A.L.T.s impact on meshwork
11
S.L.T.s impact on meshwork
12
Anecdotal Reports
  • A.L.T. doesnt 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.

13
A.L.T.
  • Performing Argon Laser Trabeculoplasy

14
Perform Gonioscopy
  • Obtain Informed Consent
  • Instill 1 gt. Iopidine or 1 gt. Alphagan-P
  • (rarely) Instill 1 gt. 1-2 Pilocarpine

15
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

16
  • Obtain blanching to whitening of tissue
    (adjust Power setting to obtain it)
  • Avoid charcoaling
  • Avoid bubbling
  • Avoid blistering

17
OrJust make it easy!
  • Set power at 1000 mWatts

18
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

19
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

20
Be Patient.
  • Need to wait for 4-6 weeks to assess efficacy of
    A.L.T.

21
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

22
S.L.T.Selective (wavelength) Laser Trabculoplasty
  • For Open Angle Forms of Glaucoma

23
S.L.T. Basics
  • Q-switched, Frequency-doubled NdYAG 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

24
Laser TrabeculoplastiesSPOT SIZES
  • ARGON procedures 50 microns
  • DIODE procedures 60 microns
  • S.L.T. procedures 400 microns

25
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26
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

27
Enhanced Housekeeping
  • Stimulate macrophages
  • Release cytokines
  • Remove metalloproteases

28
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29
S.L.T.
  • Performing Selective Wavelength Laser
    Trabeculoplasy

30
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.

31
Perform Gonioscopy
  • Obtain Informed Consent
  • Instill 1 gt. Iopidine or 1 gt. Alphagan-P
  • (rarely) Instill 1 gt. 1-2 Pilocarpine

32
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

33
Laser Lens
  • Goldman 3-Mirror
  • A.L.T. Trabeculoplasty Lens
  • Better to NOT use a Diode Trabeculoplasty Lens

34
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)

35
OrJust make it easy!
  • Set energy at 1.0mJ

36
Best to Avoid the1100 100 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

37
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

38
Post-Procedure
  • Dont 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

39
  • Dont try to judge the efficacy for at least a
    month, and 6-8 weeks is really a better time for
    assessment of treatment success

40
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

41
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?

42
Medicare Exclusion
  • 10 Days
  • And you really want to wait for at least 6 weeks
    prior to a retreatment, anyway!

43
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

44
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

45
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
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