Diabetic macular oedema and diode subthreshold micropulse laser (DIAMONDS) - study protocol for a randomised controlled trial
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2019-02-12 |
| Journal | Trials |
| Authors | Noemi Lois, Evie Gardner, Norman Waugh, Augusto AzuaraâBlanco, Hema Mistry |
| Institutions | Frimley Health NHS Foundation Trust, Manchester Royal Eye Hospital |
| Citations | 24 |
| Analysis | Full AI Review Included |
6CCVD Technical Documentation: Advanced Thermal Management for High-Performance Ophthalmic Diode Lasers
Section titled â6CCVD Technical Documentation: Advanced Thermal Management for High-Performance Ophthalmic Diode LasersâThis technical documentation analyzes the material requirements implied by the DIAMONDS study protocol, focusing on the enabling technologyâthe high-power diode laser systemsâand how 6CCVDâs Chemical Vapor Deposition (CVD) diamond materials ensure their reliability and performance.
Executive Summary
Section titled âExecutive SummaryâThe DIAMONDS study protocol outlines a critical randomized controlled trial comparing standard threshold laser versus subthreshold micropulse laser for Diabetic Macular Oedema (DMO) using 577 nm and 810 nm diode laser systems. The success and repeatability of this medical procedure rely heavily on the stability and power output of the laser source, which necessitates advanced thermal management.
- Application Focus: High-power diode lasers (577 nm and 810 nm) used in precision ophthalmic surgery (DMO treatment).
- Core Material Requirement: Extreme thermal dissipation to maintain stable wavelength and power output in compact diode laser packages.
- 6CCVD Solution: Single Crystal Diamond (SCD) and Polycrystalline Diamond (PCD) heat spreaders, offering thermal conductivity up to 2200 W/mK.
- Performance Assurance: CVD diamond ensures the diode junction temperature remains stable, preventing wavelength drift and power degradation during critical micropulse operation.
- Customization: 6CCVD provides custom-sized diamond plates and integrated metalization (e.g., Au/Pt/Ti) for direct die bonding and integration into medical laser modules.
- Quality Standard: SCD material is available with optical-grade polishing (Ra < 1 nm), suitable for use as output windows or internal optical components where high transparency is required.
Technical Specifications
Section titled âTechnical SpecificationsâThe following specifications are derived from the laser parameters and implied material requirements necessary for the reliable operation of the diode laser systems described in the DIAMONDS protocol.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Primary Laser Wavelength | 577 | nm | Optically pumped diode laser (Yellow) |
| Secondary Laser Wavelength | 810 | nm | Infrared diode laser (Commonly used in DMO trials) |
| Operating Power (Micropulse) | Up to 4x Threshold | mW | Requires stable thermal environment to prevent drift |
| Target Spot Size (Application) | 7 x 7 | spots | Applied confluently to the macular area |
| Required Thermal Conductivity (Diamond) | > 1800 | W/mK | Essential for high-power diode laser heat spreaders (SCD/PCD) |
| Required Dielectric Strength | > 106 | V/cm | Necessary for electrical isolation in laser stacks |
| Required Surface Roughness (SCD Optical) | Ra < 1 | nm | For high-quality optical windows or output couplers |
| Required Plate Dimensions | Custom | mm | Up to 125mm (PCD) or custom small chips (SCD) for die bonding |
Key Methodologies
Section titled âKey MethodologiesâThe clinical protocol dictates stringent laser operation parameters, which place high demands on the thermal stability of the diode laser components.
- Laser System Specification: The trial utilizes a 577 nm optically pumped diode laser (IRIDEX IQ 577âą) or an 810 nm infrared diode laser.
- Threshold Determination: A standard threshold is set by titrating the laser power upwards, starting from 50 mW (in 10 mW increments), until a barely visible tissue reaction is observed.
- Micropulse Power Setting: Once the threshold is identified, the laser is switched to subthreshold micropulse mode, and the power is set at 4 times the determined threshold (e.g., 200 mW).
- Confluent Application: The laser is applied confluently to the macular area using multiple 7 x 7 spot grids, requiring consistent power delivery across the treatment zone.
- Thermal Stability Requirement: The use of repetitive, very short pulses separated by long off-times is designed to reduce tissue temperature increase. This technique requires the diode laser itself to maintain exceptional thermal stability during the âonâ pulse to ensure precise energy delivery and prevent wavelength shift.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThe reliability and precision demanded by the DIAMONDS study protocol underscore the necessity of using advanced materials for critical laser components. 6CCVD is uniquely positioned to supply the CVD diamond required for the next generation of high-power ophthalmic diode lasers.
Applicable Materials
Section titled âApplicable Materialsâ| 6CCVD Material | Application in Diode Laser Systems | Key Benefit |
|---|---|---|
| Optical Grade SCD | High-power diode laser output windows, beam splitters, and internal optics. | Ra < 1 nm polishing, high transparency across visible (577 nm) and IR (810 nm) spectrum, and superior thermal management. |
| Thermal Grade SCD | Heat spreaders for individual high-power diode chips or bars. | Thermal conductivity up to 2200 W/mK, ensuring minimal junction temperature rise and maximum wavelength stability. |
| Large Area PCD | Substrates and heat sinks for larger laser modules or arrays. | Custom dimensions up to 125mm diameter, providing cost-effective thermal management for multi-chip assemblies. |
| Metalized Diamond | Ready-to-bond heat spreaders. | Custom metalization (Au, Pt, Ti, W) for eutectic or solder bonding, facilitating direct integration into laser packages. |
Customization Potential
Section titled âCustomization PotentialâThe integration of high-performance diode lasers into compact medical devices requires precise, customized components. 6CCVD offers comprehensive fabrication services to meet these needs:
- Custom Dimensions: We supply SCD and PCD plates/wafers in dimensions tailored for specific diode packages, from small die-attach chips (SCD thickness 0.1 ”m - 500 ”m) to large substrates (PCD up to 125mm).
- Precision Polishing: Our internal capability ensures SCD surfaces achieve optical quality (Ra < 1 nm) and inch-size PCD achieves Ra < 5 nm, critical for minimizing scatter and maximizing laser efficiency.
- Integrated Metalization: We provide in-house metalization services (Au, Pt, Pd, Ti, W, Cu) necessary for robust thermal and electrical contact when bonding the diode chip to the diamond heat spreader.
Engineering Support
Section titled âEngineering SupportâThe successful development of medical laser systems, such as those used in the DIAMONDS trial, requires deep expertise in material selection and thermal modeling.
- Material Selection for High-Power Density: 6CCVDâs in-house PhD team specializes in analyzing thermal load profiles to recommend the optimal diamond grade (SCD vs. PCD) and thickness required to maintain the tight wavelength tolerances necessary for precise retinal treatment.
- Global Logistics: We ensure reliable, global shipping (DDU default, DDP available) to support international manufacturing and research efforts.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
International Standard Randomised Controlled Trials, ISRCTN17742985 . Registered on 19 May 2017 (retrospectively registered).