[Diode laser-induced retinal thermal damage control with a liposome-dye system].

PURPOSE

To evaluate the feasibility of retinal thermal damage assessment in a rabbit eye model by using laser-induced release of liposome-encapsulated dye.

METHODS

After anesthesia, thermosensitive liposomes (DSPC) loaded with 5,6-Carboxyfluorescein were injected intravenously to pigmented rabbits. Retinal photocoagulations were performed with a 810 nm diode laser (p = 100 to 400 mW, phi = 500 microns, 1s) (OcuLight, IRIS Medical Instruments Inc., USA). Fluorescence measurements in the area of the laser exposures were then made with a digitized angiograph (CF-60UVi, Canon-Europe, The Netherlands; OcuLab, Life Science Resources Ltd, England).

RESULTS

Fluorescent spots were observed for power ranging from 100 +/- 5 mW to 400 +/- 5 mW. The fluorescence intensity increased linearly with the power and reached a plateau at 300 +/- 5 mW. The fluorescence intensity was correlated to the maximum temperature at the center of the laser spot with a linear increase from 42 +/- 3 degrees C to 65 +/- 3 degrees C. These results are consistent with our two previous studies with DSPC liposomes for temperature measurements in a tissue model and then in a vascular model.

CONCLUSION

This preliminary study demonstrates the possibility of a laser-induced release of liposome-encapsulated dye for a quantification of diode laser induced thermal damage in ophthalmology. Such a method could be useful for a real-time monitoring of laser photocoagulation for conditions such as choroidal neovascular membranes when a precise thermal damage is required near the foveolar area.