Comparison of morphologic changes after continuous and micro-pulse yellow laser trabeculoplasty by scanning electron microscopy

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Comparison of morphologic changes after
continuous and micro-pulse yellow laser
trabeculoplasty by scanning electron microscopy

• Wingard JB Miller KV Pokabla MJ Strunk KM
  Gray JL Bentivegna R Noecker RJ

The authors of this poster received research
funding from Research to Prevent Blindness and
the National Institutes of Health.
UPMC Eye Center, Department of
Ophthalmology University of Pittsburgh School of
Medicine Ophthalmology Visual Science Research
Center The Eye Ear Institute
wingardjb_at_upmc.edu
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PURPOSE

• To examine the morphologic trabecular meshwork
  (TM) changes resulting from a range of power
  settings for micro-pulse yellow laser
  trabeculoplasty (MYLT), in comparison to
  continuous yellow laser trabeculoplasty (CYLT).

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METHODS

• Direct laser treatment of the TM of human cadaver
  eyes.
• Iridex IQ577 laser (wavelength 577 nm) was used
  for all applications.
• Six distinct regions were treated with either
  continuous or micro-pulse laser, employing
  multiple, non-overlapping laser spots for each
  treatment in the table that follows (next slide),
  encompassing CYLT and a range of MYLT power
  setting.
• The eyes were preserved in glutaraldehyde and
  phosphate-buffered saline.
• Scanning electron microscopy was performed on
  each section to image morphologic changes due to
  the laser treatments.

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TREATMENT PARAMETERS
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RESULTS

• A range of morphologic changes was observed in
  the treated samples.
• Continuous laser produced craters and extensive
  coagulative damage to the TM.
• At higher energies, micro-pulse laser at a 15
  duty cycle showed coagulative damage.
• At lower energies, micro-pulse treated samples
  were indistinguishable from untreated controls.

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Continuous laser treatment

• Distinct crater formation is demonstrated with
  continuous yellow laser trabeculoplasty.
  craters

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Micro-pulse treatment, 2000 mW

• Micro-pulse yellow laser trabeculoplasty 2000 mW
  shows areas of coagulative damage but no crater
  formation. zone of coagulative damage

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Micro-pulse treatment, 1000 mW
Untreated control

• There is no discernible difference between
  trabecular meshwork treated with micro-pulse
  yellow laser trabeculoplasty at the 1000 mW
  setting and untreated control TM.

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CONCLUSIONS

• Morphologic evaluation of cadaver eyes after
  micro-pulse yellow laser trabeculoplasty (MYLT)
  demonstrates limited damage to the trabecular
  meshwork in comparison to eyes treated with
  continuous laser energy.
• MYLT, utilizing 100-microsecond pulses to lower
  the total energy delivered, may be a less
  destructive alternative for laser trabeculoplasty
  due to decreased thermal damage.