Laser induced retinal thermal damage control with a dye-liposome system.

Purpose To evaluate the feasibility of retinal thermal damage assessment in a rabbi t eye model by using laser-induced release of liposome-encapsulated dye. Methods After anesthesia, thermosensitive liposomes (DSPC) loaded with 5,6-Carboxyf luorescein were injected intravenously to pigmented rabbits. Retinal photoc oagulations were performed with a 810 nm diode laser (p = 100 to 400 mW, ph i = 500 mu m, 1s) (OcuLight(R), IRIS Medical Instruments Inc., USA). Fluore scence measurements in the area of the laser exposures were then made with a digitized angiograph (CF-60UVi(R), Canon-Europe, The Netherlands; OcuLab( R), Life Science Resources Ltd(R), England). Results Fluorescent spots were observed for power ranging from 100 +/- 5 m W to 400 +/- 5 mW. The fluorescence intensity increased linearly with the power and reached a plateau at 300 +/- 5 mW. The fluorescence intensity, was correla ted to the maximum temperature at the center of the laser spot with a linen s increase from 42 +/- 3 degrees C to 65 +/- 3 degrees C. These results are consistent with our two previous studies with DSPC liposomes for temperatu re measurements in a tissue model and then in a vascular model. Conclusion This preliminary study demonstrates the possibility of a laser-induced rele ase of liposome-encapsulated dye for a quantification of diode laser induce d thermal damage in ophthalmology. Such a method could be useful for al rea l-rime monitoring of laser photocoagulation for conditions such as choroida l neovascular membranes when a precise thermal damage is required near the foveolar area.