May 2003
Volume 44, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2003
Thermal and Non-Thermal Laser-Trabecular Meshwork Interaction in Human and Non-Human Primates Eyes
Author Affiliations & Notes
  • P.D. Lamar
    Bascom Palmer Eye institute, Ophthalmic Biophysics Center, Miami, FL, United States
  • V. Fernandez
    Bascom Palmer Eye institute, Ophthalmic Biophysics Center, Miami, FL, United States
  • J. Stoiber
    Bascom Palmer Eye institute, Ophthalmic Biophysics Center, Miami, FL, United States
  • N. Salas
    Dept of Biomedical Engineering/Ophthalmic Biophysics Center, Univ Miami-Bascom Palmer Eye Institute, Miami, FL, United States
  • F. Manns
    Dept of Biomedical Engineering/Ophthalmic Biophysics Center, Univ Miami-Bascom Palmer Eye Institute, Miami, FL, United States
  • S. Decker
    Dept of Cell Biology and Anatomy, Univ of Miami School of Medicine, Miami, FL, United States
  • S. Dubovy
    Dept of Cell Biology and Anatomy, Univ of Miami School of Medicine, Miami, FL, United States
  • F. Fantes
    Dept of Cell Biology and Anatomy, Univ of Miami School of Medicine, Miami, FL, United States
  • J. Parel
    Dept of Cell Biology and Anatomy, Univ of Miami School of Medicine, Miami, FL, United States
  • Footnotes
    Commercial Relationships  P.D. Lamar, None; V. Fernandez, None; J. Stoiber, None; N. Salas, None; F. Manns, None; S. Decker, None; S. Dubovy, None; F. Fantes, None; J. Parel, None.
Investigative Ophthalmology & Visual Science May 2003, Vol.44, 1162. doi:
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    • Get Citation

      P.D. Lamar, V. Fernandez, J. Stoiber, N. Salas, F. Manns, S. Decker, S. Dubovy, F. Fantes, J. Parel; Thermal and Non-Thermal Laser-Trabecular Meshwork Interaction in Human and Non-Human Primates Eyes . Invest. Ophthalmol. Vis. Sci. 2003;44(13):1162.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Abstract: : Purpose: To evaluate the thermomechanical effect of different trabeculoplasty lasers. Methods: Laser trabeculoplasty was performed on cadaver eyes with a commercially available quasi-CW high frequency Diode pumped Q-switched frequency-doubled Nd:YAG laser (532nm, 0.1s pulse duration, 50µm spot, Coherent Novus Verdi), a frequency-doubled Q switched-Nd:YAG laser (Coherent Selecta 7000, 532nm, 3ns pulse duration, 400µm spot), as well as an experimental short-pulse Titanium:Sapphire (Ti:Al2O3) laser (790nm, 7us pulse duration (200ns spike train), 175µm spot, SOLX-I). One fresh human donor-eye, 2 fresh Rhesus (Macaca mulatta) and 2 Cynomologous (Macaca fascicularis) eyes where sectioned into 8 equal parts. The iris was sutured to the sclera to expose the trabecular meshwork (TM). The tissue was placed in a custom rotating holder affixed to the slit lamp chin-rest. A single laser shot was applied in the center of each tissue sample. Treatment parameters were: 400, 600 and 800mW for the Novus Verdi laser, 1.1 to 2.4mJ for the Selecta SLT laser, and 10 to 130mJ for the Ti:Al2O3 laser. All events were video-recorded. The tissues were fixed in 2% paraformalin/2.5% Glutaraldehyde, dehydrated, critical point dried then gold coated and were systematically photographed on an JSM-35 SEM at x39, x100 or x200 and x1000 or x2000. Results: Clinical: Treatment thresholds were determined as a de-pigmentation in the area of the laser spot which were obtained at ~400mW for the Novus Verdi, ~1.5mJ for the Selecta, and ~15mJ for the Ti:Al2O3. When used above treatment threshold, all lasers produced gas bubbles. SEM: The diode laser produced shrinkage and thermal damage at all power levels that included contraction of the corneal collagen as well as of the TM’s framework. The SLT produced a tissue density increase in the region of the spot at all energies but no observable TM structural damage. With the Ti:Al2O3, no damage was detected until >80mJ where the TM lifted from its scleral wall anchors. At 135mJ, the iris separated. Conclusions: When used at threshold energy levels, the Ti:Al2O3 laser did not produce thermal or structural damage to the TM and, as with the SLT, treatment may therefore be repeated.

Keywords: trabecular meshwork • intraocular pressure 
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