Comparison Between Two Techniques of Subthreshold Diode Laser Cyclophotocoagulation in Refractory Glaucoma

The aim of this study is to assess the results of subliminal subthreshold transscleral diode cyclophotocoagulation in refractory glaucoma using the standard technique of 360 degree application and to compare the outcome with a modified technique both in terms of efficacy and safety.

Study Overview

• Status: Completed
• Conditions: Refractory Glaucoma
• Intervention / Treatment: Device: standard technique; Device: modified pattern

Detailed Description

Refractory glaucoma is glaucoma that doesn't respond favorably to surgical and/or medical treatment to lower intraocular pressure. It can include primary open angle glaucoma, primary angle closure glaucoma, neovascular glaucoma or silicone oil-induced glaucoma. Cyclophotocoagulation (CPC) is a form of cycloablation using laser to treat glaucoma. It involves ciliary body destruction by targeting the ciliary epithelium and stroma, resulting in a reduction in aqueous secretion and hence intraocular pressure. Transscleral cyclophotocoagulation using a continuous diode laser has been a treatment option in advanced glaucoma cases with s¬¬uboptimal IOP control, for a long time. High treatment energy used by diode laser cyclophotocoagulation was argued to be associated with increased frequency of serious complications such as vision loss, hypotony, and phthisis. These concerns necessitate modulation of the parameters of laser treatment used.

Micropulse transscleral cyclophotocoagulation (MP-TSCPC), which is a variation of conventional continuous-wave CPC, has emerged as an attractive alternative for the treatment of many types of glaucoma. It breaks the continuous wave laser into multiple short and repetitive pulses that allow the tissue to cool down between applications, thus reducing thermal damage. This strategy delivers very short energy pulses followed by rest periods, which is known as "duty cycle" and is defined as the ratio of time that a laser is delivering energy vs resting (ON/OFF). For this procedure, an infrared diode laser is used to stimulate the ciliary body structures and the uveoscleral pathway. This way it reduces the production of the aqueous humour and facilitates the uveoscleral outflow, with IOP reduction as a final effect.

Despite promising results, only few clinical studies are published on MP-TSCPC and most of them are retrospective studies refer to patients having previous continuous wave transscleral cyclophotocoagulation. Moreover, Several parameters and protocols have been studied in other reports in an attempt to refine the standard technique aiming to improve the outcomes without increasing the adverse effects.

• Study Type: Interventional
• Enrollment (Actual): 32
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Egypt
  • Assiut, Egypt, 71515
    • Assiut University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• patients with refractory glaucoma (IOP > 21 mmHg unresponsive to maximally tolerated antiglaucoma medications, previously failed surgical treatment, or both)

Exclusion Criteria:

• Ocular inflammation.
• Ocular infection.
• Recent ocular surgery in the study eye in the 2 months prior to enrolment.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: group A the standard technique; The tip of the probe was moved in a "painting" motion along the upper and lower hemispheres over pars plana, 3 mm behind the limbus, avoiding the 3 and 9 o'clock positions.	Device: standard technique; The probe was moved over each hemisphere for 120 seconds (a total of 240 seconds). Total energy = 2.5 x 0.313 x 240 = 187.8 J
Active Comparator: Group B a modified technique; The probe tip was moved for 2 mm perpendicular to a line 3 mm parallel to the cornea, aiming to cover the largest circumference of the ciliary body area.	Device: modified pattern; The probe was moved over 3 quadrants for 80 seconds for each quadrant (a total of 240 seconds). Total energy = 2.5 x 0.313 x 240 = 187.8 J

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
IOP reduction success rate	Success rate is defined as achieving an IOP between 5 and 21 mmHg or at least a 20% reduction in IOP at the final follow up with or without IOP lowering medications	6 months

Collaborators and Investigators

• Sponsor: Assiut University

Study record dates

Study Major Dates

• Study Start (Actual): February 1, 2022
• Primary Completion (Actual): August 1, 2024
• Study Completion (Actual): February 1, 2025

Study Registration Dates

• First Submitted: January 20, 2022
• First Submitted That Met QC Criteria: February 5, 2022
• First Posted (Actual): February 8, 2022

Study Record Updates

• Last Update Posted (Actual): July 10, 2025
• Last Update Submitted That Met QC Criteria: July 6, 2025
• Last Verified: January 1, 2022

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Eye Diseases; Ocular Hypertension; Glaucoma
• Other Study ID Numbers: CTTSDLCRG

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

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