In a meta-analysis by Hamann et al.  from 2017, a total of 3004 studies on the topic of HL+S versus endoluminal procedures (EVLA, RFA, and foam sclerotomy) were included, of which 12 could be used in the meta-analysis. The definition of a successful operation in the groups was no reflux in the treated vein after 5 years (anatomical success) and showed no significant difference between HL+S in comparison to EVLA and RFA as well as no significant difference in the occurrence of saphenofemoral recurrence detected by DUS. A significant difference in effectiveness could only be shown in comparison to foam sclerotomy; however, the meta-analysis showed that when a saphenofemoral recurrence occurred, this differed between HL+S and EVLA/RFA. After HL+S, neoangiogenesis tended to occur in the saphenofemoral region, whereby after EVLA/RFA, a recurrence occurred most frequently via the AASV .
The clinical success rate is very high for both procedures, with no significant differences
The number of saphenofemoral recurrences detected by DUS is similar for surgical and endovenous procedures; however, in surgical crossectomy there is a new formation of varicose vessel in the junction (so-called neoangiogenesis) and in endovenous procedures a recurrence occurs via the AASV. The clinical success rate is very high for both procedures, with no significant differences.
A further study by Wallace et al. from 2018  showed a 5-year anatomical success of 93% for EVLA and 85% for HL+S (n = 140 for each group). The number of saphenofemoral recurrences detected by DUS in this study did not differ between HL+S and EVLA, and the only difference was that in HL+S, neoangiogenesis occurred and in EVLA a recurrence via the AASV in the same proportions (around 15%) . A meta-analysis by Kheirelseid et al.  also from 2018 showed no significant differences between HL+S in comparison to EVLA and RFA after 5 years.
The two large German studies on this topic, Flessenkämper et al. from 2016  and Rass et al. from 2015 , are now considered. Both studies came to the result that in HL+S, significantly fewer saphenofemoral recurrences were revealed by DUS than in EVLA. For these studies it should be known that HL+S was carried out by outstanding surgeons from vein centers with longstanding experience. This is certainly not the general standard in Germany; however, in the early stages of the study, the laser technique was still in its infancy (data collection started in 2004/2005) and was carried out with low wavelengths (810 nm for Rass et al. and 980 nm for Flessenkämper et al.) and bare fibers were used. The laser energy applied in the study by Rass et al. was low and recanalization of the treated saphenous veins often occurred (62% of saphenofemoral recurrences detected by DUS!). In the study by Flessenkämper et al., in which the author of this article also participated (surgical and endovenous procedures), the laser energy was higher but the distance from the bare fibers to the junction was much more than 2 cm. The methodologically very well carried out studies of Flessenkämper et al. and Rass et al. therefore show that an HL+S carried out to a very high standard shows a low 5‑year risk of saphenofemoral recurrence of less than 10%; however, neither study showed a failure of endoluminal procedures but both clearly demonstrated that the laser power + energy as well as the distance of the laser fibers from the junction and the nature of the laser fibers play an important role for the result of endoluminal procedures.
In order to understand why not only the laser energy and power play a role in EVLA but also the wavelength and nature of the probe, the mechanism of action of EVLA must be scrutinized. There are five postulated mechanisms of action :
direct contact between fiber tip and vein wall,
thermal interaction between laser light emitted out of the fiber tip and the vein wall:
direct absorption by the vein wall of the light scattered by the blood that reaches the wall (increase in vein wall temperature),
heating the blood surrounding the fiber tip by direct laser light absorption which causes heat flows to conduct towards the wall and, upon arrival, produce an increase in wall temperature
carbonization of the fiber tip,
coagulum formation of the blood.
In bare fibers there is more carbonization of the fiber tip and, therefore, the resulting temperature profiles are practically identical for different wavelengths . Different modes of action are therefore not explainable by different wavelengths alone but more due to other parameters, such as the velocity of fiber retraction and power (watt). First with the use of radially radiating fiber tips and a defined retraction velocity could the carbonization of the fiber tip be mostly avoided and therefore the effect of the higher wavelengths with absorption by water could come into play. This means that the earlier effect of the hot needle, or the heating of the carbon on the fiber tip and therefore the damage of the vein wall up to perforation, is avoided and the laser light at 1470 nm, or now with a 1940 nm laser, heats the water in the vein wall (but of course also the erythrocytes) better. Therefore, a targeted, gentler, and even more effective occlusion of the treated vein is achieved. The use of linear endovenous energy density (LEED) alone for measurement of the energy released is in this case a senseless parameter: 50 J/cm can be achieved with 10 W and 2 mm/s retraction speed or with 0.1 W and 0.02 mm/s retraction speed (which would have no effect). Therefore, the additional information on power (watt), retraction speed, nature of the probe tip (e.g., radial or bare), and the wavelength used is essential.
The use of outpatient endovascular procedures reduces the total costs for treatment of varicose veins
The first 5‑year data with respect to the 1470 nm laser with a radial probe and segmental RFA were published by Lawson et al. in 2018 , with 97% (EVLA) or 96% (RFA) anatomical success. In 15% of the cases, a DUS-detected saphenofemoral recurrence occurred over the AASV after 5 years (n ~ 171 per group). This is a further indication of the importance of the AASV in treatment of the saphenofemoral junction.
A further interesting aspect of endovenous procedures is the consideration of the cost structure. The endovenous procedures are carried out to an increasing extent in an outpatient setting. Nevertheless, it is maintained that the endovenous procedures are more expensive in comparison to stripping operations, which are still often carried out under inpatient conditions . The proportion of outpatient operations in Germany is still clearly lower than in countries such as the USA, Canada, and Scandinavian countries . Compared to inpatient interventions, outpatient operations offer many advantages: savings in personnel and hospital costs, a more patient-oriented treatment (e.g., due to reduced mental stress especially in older patients), the possibility of more flexible schedule planning, and a lower risk of nosocomial infections [29,30,31,32]. In 2018, Jacob and Walker  investigated the German MICADO selective contract, which enables a case-related remuneration for outpatient operations replacing inpatient operations, with respect to profitability. The result was that endovenous thermal operations of the saphenous veins develop an effect for replacing inpatient treatment, despite an increase in operations induced by the supply, and lead to a reduction of costs from the perspective of the statutory health insurance . Due to the reduction of expensive inpatient stripping operations and increased use of outpatient minimally invasive endovenous procedures, the total costs for treatment of varicose veins are therefore reduced.