Title: Specifics of Anterior Segment LASER PROCEDURES A.L.T.
1Specifics 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
2Thermal Laser Trabeculoplasty
- Indications OPEN ANGLE Glaucomas
- Must be able to see the angle
3Trabeculoplasty is appropriate for
- Primary Open-angle glaucoma
- Pigmentary Glaucoma
- Pseudoexfoliative Glaucoma
- Normal Tension Glaucoma
- Angle-recession Glaucoma
4Trabeculoplasty 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
5NSU-OCO Study
- Apply SLT to 360-degrees following Angle
Recession---prior to development of ANGLE CLOSURE
GLAUCOMA ?????
6Trabeculoplasty is NOT appropriate for
- Primary Closed-angle Glaucomas
- Secondary Closed-angle Glaucomas
- Inflammatory Glaucomas
- Neovascular Glaucomas
7S.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.
8Mechanism(s) of action
- Mechanical Effects
- Photobiostimulatory Effects
9Laser//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
10A.L.T.s impact on meshwork
11S.L.T.s impact on meshwork
12Anecdotal 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.
13A.L.T.
- Performing Argon Laser Trabeculoplasy
14Perform Gonioscopy
- Obtain Informed Consent
- Instill 1 gt. Iopidine or 1 gt. Alphagan-P
- (rarely) Instill 1 gt. 1-2 Pilocarpine
15Performance 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
17OrJust make it easy!
18Post-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
19Most 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
20Be Patient.
- Need to wait for 4-6 weeks to assess efficacy of
A.L.T.
21Followup
- 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
22S.L.T.Selective (wavelength) Laser Trabculoplasty
- For Open Angle Forms of Glaucoma
23S.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
24Laser TrabeculoplastiesSPOT SIZES
- ARGON procedures 50 microns
- DIODE procedures 60 microns
- S.L.T. procedures 400 microns
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26How 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
27Enhanced Housekeeping
- Stimulate macrophages
- Release cytokines
- Remove metalloproteases
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29S.L.T.
- Performing Selective Wavelength Laser
Trabeculoplasy
30Discontinue 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.
31Perform Gonioscopy
- Obtain Informed Consent
- Instill 1 gt. Iopidine or 1 gt. Alphagan-P
- (rarely) Instill 1 gt. 1-2 Pilocarpine
32S.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
33Laser Lens
- Goldman 3-Mirror
- A.L.T. Trabeculoplasty Lens
- Better to NOT use a Diode Trabeculoplasty Lens
34Titrate 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)
35OrJust make it easy!
36Best 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
37Treat 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
38Post-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
40OUTCOMES
- 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
41When to retreat/repeat SLT?
- As soon as pressure starts rising again.
- No harm done by waiting until IOP surpasses
target IOP..but why wait?
42Medicare Exclusion
- 10 Days
- And you really want to wait for at least 6 weeks
prior to a retreatment, anyway!
43Outcomes
- 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
44COMBINATION 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
45S.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