Comparison of laser beam intensity profiles produced by photodynamic therapy (PDT) and transpupillary thermotherapy (TTT) lasers
✍ Scribed by Thomas J. Desmettre; Serge R. Mordon
- Publisher
- John Wiley and Sons
- Year
- 2005
- Tongue
- English
- Weight
- 521 KB
- Volume
- 36
- Category
- Article
- ISSN
- 0196-8092
No coin nor oath required. For personal study only.
✦ Synopsis
Background and objectives:
For photodynamic therapy (pdt) or transpupillary thermotherapy (ttt) lasers, long irradiation time (typically 1 minute or longer) is used and a large area of retina is treated. consequently, the power stability but also the light distribution within the laser beam plays a major role. this study aimed to evaluate beam intensity profiles produced by several pdt and ttt lasers.
Study design/materials and methods:
A beam profile analyzer (cohu 4812 camera connected to a lpa-300pc, spiricon, logan, ut) was used to compare the beam profiles of pdt lasers: opal (lumenis, usa); activis (quantel medical, france), visulas (zeiss, germany). spots of 2, 3, 4, and 5 mm were tested with each laser. similarly, ttt lasers: oculight slx (iridex, ca) and iridis trade mark (quantel medical, france) were evaluated with 2 and 3 mm spot diameter and power ranging from 200 to 1,000 mw.
Results:
Pdt lasers: opal had a "top hat" and homogeneous profile whatever the spot size. numerous micro-spikes and micro-nadirs of power were observed with the activis and the visulas. ttt lasers: for the iridis the beam shape was rather gaussian, but the homogeneity was reduced by micro-spikes of power. with the oculight slx the beam shape was rather top hat and only few micro-spikes or micro-nadirs of power could be disclosed.
Discussion:
The literature tends to prove that the shape and homogeneity of the beam profile could play a role on the efficacy of the treatment.
Conclusion:
Since pdt and ttt lasers display different beam profiles, this parameter should be carefully evaluated when performing clinical evaluations of pdt or ttt treatments.