1. Study Design: A single-blind, prospective, randomized controlled trial (RCT) conducted at Kafrelsheikh University Hospital to compare the efficacy and safety of 1940 nm vs. 1470 nm diode lasers for EVLA.
2. Participants: The trial will enroll 220 adult patients (110 per group) presenting with symptomatic varicose veins (CEAP C2-C6) and duplex-proven saphenous reflux with a vein diameter \bm{< 12\text{ mm}}.
3. Randomization & Blinding: Patients are randomized in a 1:1 ratio via computer-generated sequences in sealed envelopes; patients and outcome assessors are strictly blinded, while the operating surgeon is unblinded.
4. Anesthesia: Procedures are performed under ultrasound-guided Local Tumescent Anesthesia (0.1% lidocaine with sodium bicarbonate in saline) to provide analgesia, a thermal sink, and venous compression.
5. Surgical Technique: A 600-µm radial fiber is introduced through a 6F sheath and positioned 2 cm distal to the SFJ/SPJ, followed by ablation in the Trendelenburg position at a pullback speed of 1 mm/s.
6. Laser Metrics: Group I (1940 nm) will utilize lower power settings (4-6 W; target LEED 30-50 J/cm), while Group II (1470 nm) will follow standard practice guidelines (10-12 W; target LEED 60-80 J/cm).
7. Follow-up & Outcomes: Longitudinal surveillance will occur at Day 1, Day 7, 1 month, and 6 months, with the primary outcome defined as anatomical success (complete vein occlusion via duplex ultrasound at 6 months).
8. Statistical Analysis: Secondary metrics-including pain (VAS), clinical improvement (VCSS), and complications (EHIT, paresthesia)-will be analyzed via IBM SPSS, establishing a significance threshold of \bm{p < 0.05}.

Methods Study Design and Setting This will be a prospective, randomized, controlled clinical trial designed to compare Endovenous Laser Ablation (EVLA) with 1940 nm versus 1470 nm diode lasers for the treatment of varicose veins.

The study will be conducted at the Vascular and Endovascular Surgery Department of Kafrelsheikh university hospital with recruitment from the outpatient vascular clinics. The trial will adhere to the principles of the Declaration of Helsinki and follow CONSORT guidelines for randomized trials. Ethical approval will be obtained from the Institutional Research Ethics Committee prior to study initiation.

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Participants Inclusion Criteria

• Adult patients (≥18 years) diagnosed with symptomatic varicose veins.
• Clinical, etiologic, anatomic, and pathophysiologic (CEAP) classification C2-C6.
• Duplex ultrasound evidence of saphenous vein incompetence (reflux ≥0.5 seconds in standing position).
• Great saphenous vein (GSV), small saphenous vein (SSV), or accessory saphenous vein diameter suitable for endovenous treatment (<12 mm).
• Patients able to provide informed consent. Exclusion Criteria
• Prior surgical or endovenous treatment of the affected vein.
• Vein diameter >12 mm at the target segment.
• Presence of deep venous thrombosis, superficial thrombophlebitis, or congenital venous anomalies.
• Known allergy to lidocaine or components of the tumescent anesthesia solution.
• Severe comorbidities or debilitating systemic disease contraindicating the procedure.
• Pregnant or lactating women.
• Patients unable or unwilling to provide informed consent or comply with follow-up.

Randomization and Blinding Eligible patients will be randomly assigned in a 1:1 ratio to undergo Endovenous Laser Ablation (EVLA) using either a 1940 nm diode laser (Group I) or a 1470 nm diode laser (Group II).

Randomization will be performed using a computer-generated random sequence, with allocation concealed in sequentially numbered, opaque, sealed envelopes prepared by an independent researcher not otherwise involved in patient care. At the time of enrollment, each patient will select the next available envelope to determine group allocation.

Blinding will be applied as follows:

• Patients will be blinded to the wavelength used, as both procedures will appear identical from the patient perspective.
• Outcome assessors (vascular sonographers and clinicians recording VCSS and pain scores) will be blinded to group allocation to minimize assessment bias.
• Surgeons cannot be blinded to the intervention due to the technical nature of the procedure.

This approach constitutes a single-blind randomized controlled design, with blinding maintained at the level of patients and outcome assessors.

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Intervention / Technique All procedures will be performed in an operating suite under ultrasound guidance by experienced vascular surgeons trained in endovenous interventions.

Preoperative Preparation

• Preoperative venous mapping will be performed with duplex ultrasound in the standing position to identify the great saphenous vein (GSV), small saphenous vein (SSV), or accessory saphenous veins with incompetence.

• The target vein will be marked along its course on the skin.

• Patients will be placed in the supine or prone position depending on the target vein.

• Standard aseptic precautions will be observed. Anesthesia All patients will undergo local tumescent anesthesia around the target vein using a dilute solution of 0.1% lidocaine with sodium bicarbonate in saline, administered under ultrasound guidance.

• Additional anesthesia may be tailored to patient needs and institutional practice:

  • Regional nerve block (e.g., saphenous or sural nerve block) may be applied in cases with anticipated higher discomfort.
  • Spinal anesthesia may be considered for patients with bilateral disease undergoing extensive treatment.
  • Intravenous conscious sedation may be used in anxious patients or those intolerant to local anesthesia alone.

General anesthesia will not be used, as it contradicts the minimally invasive, outpatient nature of EVLA.

Access and Fiber Placement

• Ultrasound-guided percutaneous puncture will be performed, typically at the upper calf for GSV or mid-calf for SSV access.
• A 600-µm radial fiber will be introduced into the vein through a 6F introducer sheath.
• The fiber tip will be positioned 2 cm distal to the saphenofemoral or saphenopopliteal junction.

Ablation Procedure

• Group I (1940 nm): EVLA will be performed using a 1940 nm diode laser with radial fiber. Power and LEED will be adjusted according to vein diameter, with anticipated lower power and energy requirements compared with 1470 nm.

• Group II (1470 nm):

EVLA will be performed using a 1470 nm diode laser with radial fiber. Power and LEED will follow standard clinical practice guidelines for this wavelength.

• In both groups, ablation will be performed in the Trendelenburg position (30° tilt) with the fiber withdrawn at a controlled speed of approximately 1 mm/s under continuous laser emission.
• The linear endovenous energy density (LEED) will be calculated based on total delivered energy and treated vein length.

Adjunctive Procedures • Concomitant phlebectomy or sclerotherapy of tributary varicosities may be performed at the surgeon's discretion.

Postoperative Care

• Compression therapy will be applied immediately after the procedure using a class II graduated compression stocking, to be worn continuously for 5 days, followed by daytime use for an additional 2 weeks.
• Analgesics (e.g., NSAIDs or acetaminophen) will be prescribed as needed for postoperative discomfort.
• Patients will be encouraged to ambulate on the same day of the procedure.

Follow-up and Outcome Measures Follow-up Schedule

All patients will be followed at standardized intervals:

• Day 1 post-procedure
• Day 7 (1 week)
• 1 month
• 6 months At each visit, patients will undergo clinical assessment and duplex ultrasonography performed by a blinded vascular sonographer.

Primary Outcome

• Anatomical success: complete occlusion of the treated vein segment, defined as absence of flow on duplex ultrasonography at 6 months.

Secondary Outcomes

• Clinical improvement: assessed by change in Venous Clinical Severity Score (VCSS) from baseline to 6 months.

• Pain intensity: measured using the Visual Analog Scale (VAS) at 6 hours, 1 day, 7 days, 1 month, and 6 months.

• Return to normal activity: measured in days from the procedure to resumption of usual daily activities.

• Procedural parameters: including total energy delivered (J), duration of procedure (minutes), and linear endovenous energy density (LEED, J/cm).

• Adverse events:

  • Endovenous heat-induced thrombosis (EHIT), graded by duplex ultrasound.
  • Ecchymosis, paresthesia, burns, or phlebitis.
  • Need for reintervention (recanalization or incomplete ablation). Data Collection and Blinding

• All ultrasonographic and clinical evaluations will be performed by clinicians blinded to treatment allocation.

• Patient-reported outcomes (pain, return to activity) will be collected through standardized questionnaires.

Statistical Analysis Sample Size Calculation The sample size was calculated to detect a clinically meaningful difference in vein occlusion rates and postoperative pain scores (VAS) between the 1940 nm and 1470 nm groups.

• Based on prior literature, occlusion rates at 6 months are expected to be ≥95% for both wavelengths, with small differences anticipated (8,12,16).
• Detecting a difference of 10% in pain score reduction with a power of 80% and an alpha of 0.05 requires approximately 100 patients per group.
• To account for potential dropouts or loss to follow-up (~10%), a total of 220 patients (110 per group) will be enrolled.

Data Analysis

• Data will be analyzed using SPSS (version XX; IBM, Chicago, IL, USA) or equivalent statistical software.
• Continuous variables (e.g., VAS scores, LEED, procedure time) will be expressed as mean ± standard deviation (SD) or median with interquartile range (IQR), depending on distribution.
• Categorical variables (e.g., occlusion success, complication rates) will be presented as counts and percentages.

Statistical Tests

• Independent t-test or Mann-Whitney U test for comparison of continuous variables between groups.
• Chi-square test or Fisher's exact test for categorical variables.
• Repeated measures ANOVA or mixed-model analysis for longitudinal comparisons of VAS and VCSS scores across time points.
• Kaplan-Meier survival analysis may be applied to assess time-to-event outcomes such as time to recanalization.

Significance Level A two-tailed p-value < 0.05 will be considered statistically significant.

Inclusion Criteria

• Adult patients (≥18 years) diagnosed with symptomatic varicose veins.
• Clinical, etiologic, anatomic, and pathophysiologic (CEAP) classification C2-C6.
• Duplex ultrasound evidence of saphenous vein incompetence (reflux ≥0.5 seconds in standing position).
• Great saphenous vein (GSV), small saphenous vein (SSV), or accessory saphenous vein diameter suitable for endovenous treatment (<12 mm).
• Patients able to provide informed consent.

one year