Aims: The endovenous laser treatment of varicose veins has been using for several years throughout the world with clinical results comparable to traditional surgery. Nevertheless, many controversies still exist in the world literature in terms of parameters of laser generator and procedure itself. The aim of this laboratory study was the standardisation of the procedure and set-up of the optimal technical parameters to achieve maximal vein shrinkage as basic marker of successful long-term result. Material and Methods: The insufficient trunks of the long saphenous veins which were stripped during the traditional Babcock’s stripping procedure, were irradiated with the laser energy delivered by the diode generator emitting 980 nm laser beam in the laboratory settings. In total, 279 vein segments were treated. We used the power of 5W, 8W, 10W, 12W and 15W during the maximal time possible to achieve the maximal shrinkage of the saphenous vein with minimal number of perforations. The study cohort consisted of two groups – in the first group the veins were filled with the blood (n = 139), in the other one the veins were empty (n = 140) to simulate the patient’s position on the operating table. After the procedure, every vein segment was cut longitudinally, unfolded and its inner circumference was measured and compared to inner circumference of untreated part of the same venous segment. Results: Maximal shrinkage and minimal number of perforations were achieved using lower or medium power (8 to 12 W) .Circumference of shrunken vein compared to normal venous circumference (100%) was as follows: 50% (power 5W), 45% (power 8W), 40% (power 10W), 45% (power 12W) and 58.6% (power 15W). These differences are statistically significant (p < 0.001). When higher power was used (15W), the perforations and carbonisations were more frequent and total energy was lower but the difference in amount of energy delivered was not significant (p = 0.379). Conclusions: Shrinkage of the vein depends on laser power. Based on our experiments, we recommend photocoagulation with lower or medium power (8 to 12 W) and slower pull-back (0.2 to 2 mm/s) to achieve the sufficient energy per centimeter of the vein and the optimal long-term outcome.

        Key words: endovenous laser – shrinkage – laser power – perforations