July 2018
Volume 59, Issue 9
Open Access
ARVO Annual Meeting Abstract  |   July 2018
A Randomized Clinical Trial of SLT vs ALT in Patients Who Have Already Received 360 Degrees of SLT-The Canadian Laser Study Trial Network.
Author Affiliations & Notes
  • William Hodge
    Ophthalmology, Western University, London, Ontario, Canada
  • Cindy M L Hutnik
    Ophthalmology, Western University, London, Ontario, Canada
  • Andrew C Crichton
    Ophthalmology, University of Calgary, Calgary, Alberta, Canada
  • Bryce Ford
    Ophthalmology, University of Calgary, Calgary, Alberta, Canada
  • Catherine M Birt
    Ophthalmology, University of Toronto, Toronto, Ontario, Canada
  • Marcelo T Nicolela
    Ophthalmology, Dalhousie University, Halifax, Nova Scotia, Canada
  • Lesya Shuba
    Ophthalmology, Dalhousie University, Halifax, Nova Scotia, Canada
  • Karim F Damji
    Ophthalmology, University of Alberta, Edmonton, Alberta, Canada
  • Michael Dorey
    Ophthalmology, University of Alberta, Edmonton, Alberta, Canada
  • Enitan Sogbesan
    Ophthalmology, mcMaster University, Hamilton, Ontario, Canada
  • Hady Saheb
    Ophthalmology, mcGill University, Montreal, Quebec, Canada
  • Hui Guo
    Ophthalmology, Western University, London, Ontario, Canada
  • Neil Klar
    Ophthalmology, Western University, London, Ontario, Canada
  • Footnotes
    Commercial Relationships   William Hodge, None; Cindy Hutnik, None; Andrew Crichton, None; Bryce Ford, None; Catherine Birt, None; Marcelo Nicolela, None; Lesya Shuba, None; Karim Damji, None; Michael Dorey, None; Enitan Sogbesan, None; Hady Saheb, None; Hui Guo, None; Neil Klar, None
  • Footnotes
    Support  CIHR MOP123233
Investigative Ophthalmology & Visual Science July 2018, Vol.59, 3461. doi:https://doi.org/
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      William Hodge, Cindy M L Hutnik, Andrew C Crichton, Bryce Ford, Catherine M Birt, Marcelo T Nicolela, Lesya Shuba, Karim F Damji, Michael Dorey, Enitan Sogbesan, Hady Saheb, Hui Guo, Neil Klar; A Randomized Clinical Trial of SLT vs ALT in Patients Who Have Already Received 360 Degrees of SLT-The Canadian Laser Study Trial Network.. Invest. Ophthalmol. Vis. Sci. 2018;59(9):3461. doi: https://doi.org/.

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

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Abstract

Purpose : To compare the 1 year IOP lowering effect between selective laser trabeculoplasty (SLT) and argon laser trabeculoplasty (ALT) on patients who were already treated with 360-degree SLT previously.

Methods : This is the first multicenter, patient-masked, RCT looking at SLT repeatability. It was a multicenter RCT performed at 7 Canadian centers and funded by The Canadian Institute for Health Research. The study recruited 137 patients and met its a priori sample size/power calculations. This is the first public presentation of this work.

Results : We enrolled all participants between February 14, 2013 to October 24, 2016. Randomization was balanced. Diagnosis included primary open angle glaucoma (POAG), pigmentary dispersion syndrome (PDS), pseudoexfoliation syndrome (PXF), and ocular hypertension (OHT). Baseline IOP was 21.67 mmHg (SD 3.15) in the SLT group and 21.77 mmHg (SD 3.35) in the ALT group. At 12-month follow-up, mean IOP reduction was 3.35 mmHg (SD 4.96) for the SLT arm and 3.36 (SD 5.06) for the ALT arm. The difference was -0.01 mmHg (95% CI, -1.86 to 1.84; p = 0.99) for the complete cases and 0.86 mmHg (95% CI, -0.68 to 2.41; p = 0.27) for the patients without protocol deviation. One patient (2%) in the SLT group and 4 (7%) in the ALT group progressed to surgery (RR 0.25 p = 0.22). No IOP spike (IOP elevation > 5 mmHg at 1 hour) was detected in either group.

Conclusions : There are two main conclusions from this study: (1) 180-degree SLT is effective when done after previous complete SLT but ALT can also be used with equal effectiveness in this setting. (2) Although both lasers were effective, IOP reduction was only about 50%-67% of what is typically obtained from laser angle surgery in laser naive eyes. We hypothesize that original SLT does cause some anatomical or physiological change to the trabecular meshwork as efficacy of BOTH SLT and ALT is reduced after initial SLT. An ongoing open label study of these patients is in progress to determine the IOP lowering effects of even further SLT treatments.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.

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