gms | German Medical Science

Background/Purpose: Subthreshold laser treatments using a repetitive microsecond pulse evolved for the treatment of CSCR and DME. No consolidated recommendation for parameter selection was established. This literature review aims to identify an appropriate treatment scheme for subthreshold treatments with yellow wavelength lasers.

Methods: Peer reviewed publications have been extracted. The results have been reviewed for laser parameters, titration & power calculation as well spot/plan methodology and the corresponding safety and efficacy profile.

Results: Within pubmed.org 10 peer reviewed publications could have been extracted. Among them 2 studies using endpoint management (PASCAL®) and one experimental study using animal models can be found. One case report presents a failure of a parameter set. The remaining 6 studies publish positive results with respect to safety and efficacy of the used parameter set. In none of the pure microsecond pulse laser strategies a specific parameter set had been used twice. There is a trend towards usage of 15% DC. However no consolidation could have been found in either spot size settings (100µm vs 200µm), pulse durations (20ms vs. 200ms) or power definition. 30% of threshold energy is reported to present a non destructive setting. Considering the current trend of placing confluent grids over edematous areas it seems to be most efficient to use 200µm spot size and 100ms pulse duration for optimizing time and fluence. With respect to titration method, there is a trend toward titration in cw mode, even if fixed power methods and titration in micropulse settings have been attempted.

Conclusion: Based on current literature there cannot be concluded on a specific parameter set. However evidence is present that 15% DC, 100ms and 200µm and titration cw and double the power after switch to microsecond pulsing mode represents a safe and effective parameter set.