How to Choose a Radial Fiber: Diameter & Length Guide | MedFiber

Introduction: The Right Tool for the Right Vein

Understanding the advantages of 360° radiation is the first step. The next, critical step is selecting the correct Radial Fiber for the specific vein you’re treating. A mismatch between fiber specifications and venous anatomy can compromise the very benefits—uniformity, safety, and efficiency—that make radial technology superior. This guide cuts through the technical jargon to give you a clear, actionable framework for choosing the perfect radial fiber every time.

The Primary Decision: Fiber Diameter (µ)

The fiber’s outer diameter is the most crucial specification, directly tied to the size of the target vein.

The Golden Rule: Fiber Diameter ≤ Vein Diameter

The fiber must fit comfortably within the vein to allow for centering and even radiation. A fiber that is too large risks wall contact and friction during pullback.

Vein Diameter (Ultrasound Measurement)	Recommended Radial Fiber Diameter	Clinical Rationale
Small Veins (3-5 mm)	400 µm (0.4 mm)	Provides optimal fit in smaller saphenous tributaries or recurrent varicosities. Ensures space for tumescent anesthesia around the fiber.
Standard GSV/SSV (5-8 mm)	600 µm (0.6 mm)	The workhorse size for treating the great and small saphenous veins. Balances energy delivery and maneuverability.
Large or Dilated Veins (8-12 mm+)	800 µm (0.8 mm) or 1000 µm (1.0 mm)	Larger diameter fibers have a more robust structure and can help maintain position in sizable veins, ensuring consistent wall contact for the 360° radiation.

> Pro Tip: Always err on the side of a slightly smaller fiber if the vein measurement is borderline. The uniform 360° radiation pattern is effective even with a small gap, whereas a tight fit can cause procedural issues.

The Practical Consideration: Working Length (cm)

Length determines the maximum treatment segment you can ablate without needing to reposition the fiber or laser system.

Short Lengths (50-100 cm): Ideal for focal treatments, such as perforator ablation or short segments of reflux. Offers greater pushability and control.

Standard Lengths (150-200 cm): The most common choice for complete truncal ablations (e.g., entire GSV). Allows treatment from the knee to the SFJ without interruption.

Key Question: What is the distance from your laser system to the patient’s treatment site? Ensure the fiber length accommodates this path with comfortable slack.

Decoding the Specification Sheet: Beyond Diameter and Length

Don’t overlook these technical details that ensure performance and safety.

Core Specifications

Numerical Aperture (NA): Impacts the radiation angle. A standard, optimized NA ensures the perfect 360° ring pattern without “hot ends.”

Transmission Efficiency (> 85%): A higher percentage means more laser energy is delivered to the vein wall, not lost within the fiber itself. Check our Radial Fiber product specifications for guaranteed values.

Sterilization & Packaging (A Safety Mandate)

Ethylene Oxide (EtO) Sterilization: The medical-grade standard. Ensure the package is individually sealed and labeled with a valid sterility expiration date.

Packaging Integrity: Inspect the package for damage before use. A compromised seal invalidates sterility.

Laser System Compatibility

This is non-negotiable. The fiber must match your laser’s:

Wavelength (e.g., 1470 nm, 980 nm).

Connector Type (e.g., SMA, D80).

A mismatch can damage your laser or the fiber, void warranties, and pose a safety risk.

Scenario-Based Selection: Putting It All Together

Let’s apply the framework to common clinical cases.

Case 1: Straightforward GSV Ablation

Vein: 6mm GSV from SFJ to knee. Choice: 600 µm diameter, 150 cm length. Standard fiber for the job. Why: Perfect size match, sufficient length for full treatment.

Case 2: Complex Reticular Vein Cluster

Vein: Multiple 3-4mm tortuous tributaries. Choice: 400 µm diameter, 100 cm length. Why: Smaller diameter navigates turns easily; shorter length offers better tactile feedback for precision work.

Case 3: Large, Dilated Accessory Vein

Vein: 10mm anterior accessory saphenous vein. Choice: 800 µm or 1000 µm diameter, standard length. Why: Larger diameter ensures the fiber remains centered to deliver effective circumferential radiation in a big lumen.

Pre-Use Checklist: Your Final Verification

Before opening the package, confirm:

Patient & Procedure: Fiber matches the planned vein’s diameter and length.

Laser Compatibility: Wavelength and connector are correct.

Packaging: Sterile seal is intact, expiry date is valid.

Backup Plan: A spare fiber of the same spec is available.

Choosing correctly maximizes the benefits you’ve read about in our comparison of Radial Fiber vs. Bare-Tip Fibers and ensures the smooth execution outlined in our EVLT Step-by-Step Guide.

Conclusion: Precision Selection for Predictable Results

Selecting a radial fiber is not a generic task. It is a pre-operative decision as important as choosing the correct laser setting. By systematically considering vein diameter → fiber diameter → working length → technical specs → compatibility, you transform a powerful technology into a predictable, safe, and optimized tool for every patient.

Your final step? Proper handling and maintenance to protect your investment and ensure performance. In our next guide, we will cover the essential Cleaning and Best Practices for Radial Fiber Maintenance to complete your expertise.