Clarifying the Optimal Application of SLT Therapy Trial (COAST)

September 26, 2025 updated by: Balasubramani Goundappa, University of Pittsburgh
The goal of this study is to understand if SLT performed at low energy is as effective as SLT performed at standard energy, and also to see if repeating SLT at low energy once a year will prevent or delay the need for daily eye drop medications better than waiting for SLT to wear off before repeating it.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

790

Phase

  • Phase 3

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • Canada
    • Ontario
      • Kitchener, Ontario, Canada, N2A0K5
        • Active, not recruiting
        • Ocular Health Centre
  • United States
    • California
      • Laguna Hills, California, United States, 92653
        • Recruiting
        • Harvard Eye Associates
        • Principal Investigator:
          • Ye Elaine Wang, MD
        • Contact:
      • Pasadena, California, United States, 91105
        • Recruiting
        • Doheny Eye Center UCLA
        • Principal Investigator:
          • Judy L Chen, MD
        • Contact:
      • Sacramento, California, United States, 95817
        • Recruiting
        • University of California, Davis
        • Principal Investigator:
          • James Brandt, MD
        • Contact:
      • San Francisco, California, United States, 94158
        • Recruiting
        • University of California, San Francisco
        • Principal Investigator:
          • Ying Han, MD
        • Contact:
    • Colorado
      • Sheridan, Colorado, United States, 80110
        • Recruiting
        • Mile High Eye Institute
        • Principal Investigator:
          • Zachary Vest, MD
        • Contact:
    • Florida
      • Lakeworth, Florida, United States, 33467
        • Recruiting
        • Clear Vue Laser Eye Center
        • Contact:
        • Principal Investigator:
          • Monique Barbour, MD
    • Illinois
      • Chicago, Illinois, United States, 60615
        • Recruiting
        • Northwestern Medical Group
        • Principal Investigator:
          • Angelo Tanna, MD
        • Contact:
      • Orland Park, Illinois, United States, 60467
        • Recruiting
        • Chicago Arbor Eye Institute
        • Contact:
        • Principal Investigator:
          • Richard Quinones, MD
      • Peoria, Illinois, United States, 61615
    • Maryland
      • Baltimore, Maryland, United States, 21287
        • Recruiting
        • Wilmer Eye Institute Johns Hopkins
        • Principal Investigator:
          • Pradeep Ramulu, MD
        • Contact:
    • Massachusetts
      • Boston, Massachusetts, United States, 02114
        • Recruiting
        • Massachusetts Eye and Ear
        • Principal Investigator:
          • Michael Lin, MD
        • Contact:
      • Boston, Massachusetts, United States, 02451
        • Recruiting
        • Ophthalmic Consultants of Boston
        • Principal Investigator:
          • Theodor Sauer, MD
        • Contact:
      • Reading, Massachusetts, United States, 01867
        • Recruiting
        • Mark Latina, LLC
        • Contact:
        • Principal Investigator:
          • Mark Latina, MD
    • Michigan
      • Ann Arbor, Michigan, United States, 48105
        • Recruiting
        • University of Michigan Kellogg Eye Center
        • Contact:
        • Principal Investigator:
          • Amanda Bicket, MD
      • Detroit, Michigan, United States, 48201
        • Recruiting
        • Kresge Eye Institute Wayne State University
        • Contact:
        • Principal Investigator:
          • Bret Hughes, MD
    • New York
      • The Bronx, New York, United States, 10469
        • Recruiting
        • New York Eye Surgery Associates
        • Contact:
        • Principal Investigator:
          • Nathan Radcliffe, MD
    • Ohio
      • Cleveland, Ohio, United States, 44195
        • Recruiting
        • Cleveland Clinic Cole Eye Institute
        • Principal Investigator:
          • Ang Li, MD
        • Contact:
      • Cleveland, Ohio, United States, 44106
        • Recruiting
        • University Hospitals Eye Institute
        • Contact:
        • Principal Investigator:
          • Douglas Rhee, MD
    • Oregon
      • Portland, Oregon, United States, 97210
        • Recruiting
        • Devers Eye Institute
        • Contact:
        • Principal Investigator:
          • Robert Kinast, MD
    • Pennsylvania
      • Kingston, Pennsylvania, United States, 18704
        • Recruiting
        • Eye Care Specialists
        • Principal Investigator:
          • Daniel Lutz, MD
        • Contact:
      • Philadelphia, Pennsylvania, United States, 19107
        • Recruiting
        • Wills Eye Hospital
        • Principal Investigator:
          • Lauren Hock, MD
        • Contact:
      • Philadelphia, Pennsylvania, United States, 19104
      • Pittsburgh, Pennsylvania, United States, 15213
        • Active, not recruiting
        • UPMC Eye Center
    • Tennessee
      • Nashville, Tennessee, United States, 37232
        • Recruiting
        • Vanderbilt Eye Institute
        • Contact:
        • Principal Investigator:
          • Rachel Kuchtey, MD
    • Texas
      • Fort Worth, Texas, United States, 76102
        • Recruiting
        • Ophthalmology Associates
        • Principal Investigator:
          • Brian Flowers, MD
        • Contact:
    • Washington
      • Spokane, Washington, United States, 99204
        • Recruiting
        • Spokane Eye Clinical Research
        • Contact:
        • Principal Investigator:
          • Rory Allar, MD
    • West Virginia
      • Morgantown, West Virginia, United States, 26505
        • Recruiting
        • West Virginia University
        • Contact:
        • Principal Investigator:
          • Tony Realini, MD, MPH
    • Wisconsin
      • Madison, Wisconsin, United States, 53705
        • Recruiting
        • University of Wisconsin-Madison
        • Contact:
        • Principal Investigator:
          • Yao Liu, MD

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  1. Age 18 or older and in good health

  2. Each eye with one of the following qualifying diagnoses (diagnoses may differ between eyes):

    1. High-risk ocular hypertension (OHT): IOP > 21 mmHg without glaucomatous optic neuropathy (excavation, diffuse or focal thinning or notching of the neuroretinal rim, visible nerve fiber layer defects, or asymmetry of the vertical cup-to-disc ratio of >0.2 between eyes)
    2. Mild primary open-angle glaucoma: glaucomatous optic neuropathy, visual field mean deviation better than -6.0 dB with no points in the central 5° <15 dB (see figure on next page)
    3. Moderate primary open-angle glaucoma: glaucomatous optic neuropathy, visual field mean deviation equal to or worse than -6.0 dB but no worse than -12.0 dB and no central 5° points <15 dB or mean deviation -12.0 dB or better with 1 central 5° points <15 dB (see figure on next page).
  3. Each eye with BCVA 20/200 (UK 6/60) or better

Exclusion Criteria:

  1. Use of topical IOP-lowering medications for more than 6 cumulative months at any time in the past 5 years (this is a modification implemented during active enrollment)
  2. Any history of IOP-lowering laser (prophylactic iridotomy not included) or surgical procedure
  3. Advanced POAG in either eye (worse than moderate POAG as defined above)
  4. Glaucoma other than POAG (including pigmentary and pseudoexfoliation glaucoma) in either eye
  5. Mean IOP > 35 mmHg at either the screening or baseline visit in either eye
  6. Narrow or closed angle (Shaffer Grade 0, 1, or 2) in either eye
  7. Contraindications to SLT or any other study intervention
  8. Any corneal pathology that would preclude accurate assessment of IOP by Goldmann tonometry in either eye
  9. Any intraocular surgical procedure within the past 6 months in either eye
  10. Inability to attend all scheduled study visits
  11. Pregnant or planning to become pregnant in the next 4 years

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Active Comparator: Trial 1: Initial standard energy SLT
Standard energy SLT is performed as follows: beginning at 0.8 mJ, energy will be titrated up or down within the first 5-10 spots until champagne bubbles are visualized with every 2nd or 3rd spot. Energy can be titrated throughout the procedure, in response to variations in pigmentation, to ensure the appearance of champagne bubbles with every 2nd or 3rd spot throughout the full 360° treatment. Energy should be increased if no bubbles are seen with 5 consecutive spots and decreased if bubbles are seen with 5 consecutive spots.
Procedure: Standard Energy SLT
SLT performed at standard energy
Experimental: Trial 2: Month 12 Randomization: Annual Low Energy Repeat SLT

At month 12, eligible subjects will be randomized to undergo repeat SLT either annually at low energy or as needed at standard energy.

Low energy SLT will consist of 100 treatment spots delivered at 0.4 mJ per spot throughout the full 360° treatment, with the exception that energy can be reduced to 0.3 mJ if bubbles are seen with 5 consecutive spots and can be increased back to a maximum of 0.4mJ is no bubbles are seen with 5 consecutive spots.
Procedure: Low Energy SLT
SLT performed at low energy
Active Comparator: Trial 2: Month 12 Randomization: As-Needed Repeat SLT at Standard Energy

At month 12, eligible subjects will be randomized to undergo repeat SLT either annually at low energy or as needed at standard energy.

Standard SLT will be performed as follows: beginning at 0.8 mJ, energy will be titrated up or down within the first 5-10 spots until champagne bubbles are visualized with every 2nd or 3rd spot. Energy can be titrated throughout the procedure, in response to variations in pigmentation, to ensure the appearance of champagne bubbles with every 2nd or 3rd spot throughout the full 360° treatment. Energy should be increased if no bubbles are seen with 5 consecutive spots and decreased if bubbles are seen with 5 consecutive spots.
Procedure: Standard Energy SLT
SLT performed at standard energy
Experimental: Trial 1: Initial Low Energy SLT

Note: This arm was discontinued following a planned interim analysis.

Low energy SLT will consist of 100 treatment spots delivered at 0.4 mJ per spot throughout the full 360° treatment, with the exception that energy can be reduced to 0.3 mJ if bubbles are seen with 5 consecutive spots and can be increased back to a maximum of 0.4mJ if no bubbles are seen with 5 consecutive spots.
Procedure: Low Energy SLT
SLT performed at low energy

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
12-month survival
Time Frame: 12 months
Survival of first SLT through Month 12
12 months
48-month survival
Time Frame: 48 months
At Month 12, subjects are randomized to repeat SLT either annually at low energy or PRN at standard energy. The proportion controlled with SLT alone at Month 48 will be compared between groups
48 months

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Mean IOP
Time Frame: 12 months
Mean IOP at month 12
12 months
Long-term mean IOP
Time Frame: 12, 24, 36, and 48 months
Mean IOP at each study visit
12, 24, 36, and 48 months
Incidence of IOP spikes
Time Frame: 0, 12, 24, 36, and 48 months
IOP spikes > 5 mmHg on day of SLT
0, 12, 24, 36, and 48 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University of Pittsburgh

Collaborators

National Eye Institute (NEI)
West Virginia University

Investigators

  • Principal Investigator: Stephen Wisniewski, PhD, University of Pittsburgh
  • Study Chair: Tony Realini, MD, MPH, West Virginia University
  • Principal Investigator: Goundappa K Balasubramani, PhD, University of Pittsburgh

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Helpful Links

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

September 7, 2021

Primary Completion (Estimated)

June 30, 2027

Study Completion (Estimated)

August 31, 2027

Study Registration Dates

First Submitted

June 27, 2021

First Submitted That Met QC Criteria

July 19, 2021

First Posted (Actual)

July 20, 2021

Study Record Updates

Last Update Posted (Estimated)

October 2, 2025

Last Update Submitted That Met QC Criteria

September 26, 2025

Last Verified

September 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • STUDY21060171
  • UG1EY031654 (U.S. NIH Grant/Contract)
  • UG1EY031651 (U.S. NIH Grant/Contract)
  • STUDY21080018 (Other Identifier: University of Pittsburgh)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

All study data will be de-identified. We will invite other investigators to submit secondary data requests using the data from the study and will work with those investigators to foster additional research studies and manuscripts. The investigators agree to abide by the principles for sharing research resources as described by "Principles and Guidelines for Recipients of NIH Research Grants and Contracts on Obtaining and Disseminating Biomedical Research Resources." All publications based on the study will adhere to the NIH Public Access Policy (Notice NOT-OD-08-033). At the end of the study, all study data will be submitted for permanent archive per the notice of grant award.

IPD Sharing Time Frame

At study completion

IPD Sharing Access Criteria

See above

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • SAP
  • ICF

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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