Long-term Results of Mini Asymmetric Radial Keratotomy for the Treatment of Keratoconus
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2018-01-01 |
| Journal | International Journal of Keratoconus and Ectatic Corneal Diseases |
| Authors | Marco Abbondanza, Gabriele Abbondanza, Valentina De Felice |
| Institutions | The University of Sydney |
| Citations | 1 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: MPCVD Diamond for Precision Ophthalmic Surgery
Section titled “Technical Documentation & Analysis: MPCVD Diamond for Precision Ophthalmic Surgery”This document analyzes the long-term results of Mini Asymmetric Radial Keratotomy (MARK) for Keratoconus, focusing on the critical role of ultra-precision cutting tools. The requirement for customized, highly controlled incisions (depth at 80% corneal thickness, length 1.75-2.25 mm) necessitates the use of Single Crystal Diamond (SCD) knives, a core product offering of 6CCVD.
Executive Summary
Section titled “Executive Summary”- Application Validation: The study confirms the long-term efficacy (7.3 years average follow-up) of MARK surgery for stabilizing moderate to mild progressive Keratoconus (Kc).
- Precision Tooling Requirement: The MARK procedure relies on highly customized, centripetal mini-incisions performed with a calibrated diamond knife, demanding atomic-level sharpness and dimensional stability.
- Key Outcome Metrics: Significant clinical improvement was observed, including a 98% improvement rate in mean pachymetry (+38 µm increase in corneal thickness) and a 95% improvement in best spectacle-corrected visual acuity (BSCVA).
- Methodology: Incisions were customized based on tomography/topography, limited to 80% of corneal thickness, and restricted to the affected sector, minimizing invasiveness.
- Material Necessity: The success of this ultra-precision incisional technique validates the need for high-quality, defect-free Single Crystal Diamond (SCD) materials for advanced ophthalmic surgical instruments.
- 6CCVD Value Proposition: 6CCVD provides the necessary high-purity, low-defect SCD plates and custom fabrication services required for manufacturing next-generation calibrated diamond surgical blades.
Technical Specifications
Section titled “Technical Specifications”The following data points highlight the precision required for the MARK procedure and the resulting long-term clinical stability achieved through precise incisional surgery.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Average Follow-up Period | 7.3 | Years | Long-term stability assessment |
| Preoperative Mean Keratometry (Kavg) | 47.25 | D | Corneal steepness before MARK |
| Postoperative Mean Keratometry (Kavg) | 44.61 | D | Value after 6 years follow-up |
| Mean Pachymetry Improvement | +38 | µm | Increase in corneal thickness (446 µm to 484 µm) |
| Visual Acuity Improvement Rate (BSCVA) | 95 | % | Patients showing improved visual acuity |
| Incision Length (Mini-incisions) | 1.75 - 2.25 | mm | Very short, customized incisions |
| Incision Depth | ~80 | % | Of total corneal thickness (critical precision requirement) |
| Postoperative BSCVA (LogMAR) | 0.095 | LogMAR | Equivalent to 7.7/10 visual acuity |
| Corneal Diameter Limit (Peripheral) | 8 | mm | Incisions do not extend beyond this diameter |
Key Methodologies
Section titled “Key Methodologies”The MARK procedure is highly customized and relies on strict control over the geometry and depth of the corneal incisions, requiring specialized diamond tooling.
- Patient Selection: Inclusion criteria were progressive stages I and II Keratoconus (Kc) and contact lens intolerance; advanced stages and ocular infections were excluded.
- Surgical Planning: Tomography- and topography-guided planning was used to customize the number (3-5), position, length, and depth of the centripetal mini-incisions.
- Tooling: A calibrated diamond knife (Meyco) and custom-made double concentric corneal markers were utilized to ensure precise placement and depth control.
- Incision Parameters: Incisions were performed sectorally, limited to the portion of the cornea where Kc was manifest.
- Depth Control: Incision depth was strictly controlled to approximately 80% of the corneal thickness to ensure stability while minimizing risk.
- Length Control: Incisions were limited to 1.75-2.25 mm in length, constrained externally (7.5-8 mm diameter) and internally (3.5-4 mm diameter).
- Anesthesia and Postoperative Care: Topical anesthesia (benoxinate chloride 0.4%) was used, followed by a bandage contact lens, topical antibiotics, and NSAIDs.
6CCVD Solutions & Capabilities
Section titled “6CCVD Solutions & Capabilities”The success of MARK surgery hinges on the ability of the surgical blade to create ultra-sharp, highly controlled incisions at a precise depth (80% of 446 µm). This level of precision is only achievable using Single Crystal Diamond (SCD) tooling. 6CCVD is the ideal partner for manufacturers of precision ophthalmic surgical instruments.
Applicable Materials
Section titled “Applicable Materials”To replicate or extend the precision required for the calibrated diamond knife used in this research, Optical Grade Single Crystal Diamond (SCD) is mandatory.
- Material: Optical Grade SCD (Low Nitrogen, Low Defect Density).
- Requirement Match: SCD provides the unmatched hardness, chemical inertness, and ability to achieve an atomically sharp cutting edge (Ra < 1nm) necessary for controlled, minimally invasive corneal incisions.
- Alternative Consideration: For non-optical components or mounting fixtures requiring high thermal stability, Polycrystalline Diamond (PCD) substrates could be utilized.
Customization Potential for Surgical Tooling
Section titled “Customization Potential for Surgical Tooling”6CCVD’s advanced MPCVD growth and fabrication capabilities directly address the needs of precision surgical instrument manufacturers:
| Capability | 6CCVD Specification | Relevance to MARK Surgery |
|---|---|---|
| Material Purity | High-purity, low-defect SCD | Ensures maximum edge strength and longevity for repeated calibration and use. |
| Polishing & Edge Quality | SCD Polishing: Ra < 1 nm | Critical for achieving the ultra-sharp, defect-free cutting edge required for 80% depth control without microperforations. |
| Custom Dimensions | Plates/wafers up to 125 mm (PCD); SCD up to 10x10 mm | Provides the base material for custom blade geometries and mounting fixtures. |
| Thickness Control | SCD: 0.1 µm - 500 µm | Allows for precise control over the diamond blade’s geometry and stiffness. |
| Metalization Services | Au, Pt, Pd, Ti, W, Cu (Internal) | Essential for bonding the SCD blade to the surgical handle or calibration mechanism (e.g., Ti/Pt/Au stack for robust adhesion). |
| Laser Cutting/Shaping | Custom laser shaping and dicing | Enables the creation of complex, customized blade profiles and markers referenced in the study. |
Engineering Support
Section titled “Engineering Support”6CCVD’s in-house PhD team specializes in optimizing diamond material properties for extreme applications. We can assist surgical tool manufacturers with:
- Material Selection: Choosing the optimal SCD grade (e.g., specific crystallographic orientation) to maximize blade durability and sharpness for Precision Ophthalmic Incision projects.
- Interface Engineering: Designing robust metalization layers for secure, biocompatible mounting of the diamond blade into calibrated surgical handles.
- Quality Assurance: Providing detailed material characterization (e.g., defect mapping, surface roughness) to guarantee the highest quality control for medical devices.
Call to Action: For custom specifications or material consultation regarding high-precision surgical diamond tooling, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Aim: To present long-term results of mini asymmetric radial keratotomy (MARK) for the treatment of mild to moderate keratoconus, with an average follow-up of 7.3 years and a minimum of 6 years.Design: Retrospective clinical study. Materials and methods:The postoperative outcomes of 66 eyes (45 patients) were selected and retrospectively analyzed.Inclusion criteria were progressive stages I and II keratoconus (Kc) and contact lens intolerance, while exclusion criteria were advanced stages of the pathology and chronic or recurrent ocular infections.Tomography-and topography-guided miniincisions were customised and performed sectorally with a calibrated diamond knife and custom-made corneal markers.Results: After a minimum follow-up of 6 years, mean keratometry improved in 91% of cases (from 47.25 D to 44.61 D), and mean pachymetry improved in 98% of cases (from 446 μm to 484 μm), while best spectacle-corrected visual acuity improved for 95% of patients, from 0.23 LogMAR (5.9/10) to 0.095 LogMAR (7.7/10). Conclusion:MARK improved both mean keratometry and mean pachymetry, thus halting the progression of keratoconus, while improving visual acuity.The long-term results suggest that MARK should be considered as one of the conservative treatments for moderate to mild progressive keratoconus.