805-nm diode-laser-induced release of liposome-encapsulated dye for quantification of chorioretinal thermal damage: in-vivo study on a rabbit eye model

摘要

This study aimed to evaluate the feasibility of retinal thermal damage assessment in a rabbit eye model by using laser-induced release of liposome-encapsulated dye. After anethesia, thermosensitive liposomes (DSPC) loaded with 5,6-Carboxyfluorescein were injected intravenously to pigmented rabbits. Retinal photocoagulation were performed with a 810 nm diode laser (P equals 100 to 400 mW, $Phi equals 500 micrometer, ls). Fluorescence measurements in the area of the laser exposures were then realized with a digitized angiograph. Histology was performed on retinal tissue and adjacent ares. Fluorescent spots were observed for fluences ranging from 50 plus or minus 10 J/cm$+2$/ to 210 plus or minus 10 J/cm$+2$/. The fluorescence intensity increased linearly with the fluence and reached a plateau at 150 plus or minus 10 J/cm$+2$/. The fluorescence intensity was correlated to the maximum temperature at the center of the laser spot with a linear increase from 42 plus or minus 3 degrees Celsius to 65 plus or minus 3 degrees Celsius. The chorioretinal thermal damage quantified by histology was correlated to temperature. These results are in agreement with our two previous studies with DSPC liposomes for temperature measurements in a tissue model and then in a vascular model. In conclusion, this 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 condition such as choroidal neovessels when a precise thermal damage is required near the foveolar area.