Diode laser-induced thermal damage evaluation on the retina with a liposome dye system.
OBJECTIVE
The aim of the study was 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 (DiStearoyl Phosphatidyl Choline: DSPC) loaded with 5,6-carboxyfluorescein were injected intravenously to pigmented rabbits. Retinal photocoagulations were performed with a 810nm diode laser (P=100-400 mW, laser spot=500 microm, 1s) (OcuLight, IRIS Medical Instruments, Mountain View, CA). Fluorescence measurements in the area of the laser exposures were then realized with a digitized angiograph (CF-60UVi, Canon-Europe, The Netherlands; OcuLab, Life Science Resources, UK).


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 280 +/- 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 in agreement with our two previous studies with DSPC liposomes for temperature measurements in a tissue model and then in a vascular model.


CONCLUSIONS
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.
INSERM, French National Institute of Health and Medical Research, Lille.
T J
TJ
Desmettre
S
S
Soulie-Begu
J M
JM
Devoisselle
S R
SR
Mordon
D000818:Animals; D004195:Disease Models, Animal; D005126:Eye Burns / Q000175:diagnosis* / Q000209:etiology; D005451:Fluorescein Angiography / Q000379:methods*; D005452:Fluoresceins / Q000032:analysis*; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000032:analysis*; D006358:Hot Temperature / Q000009:adverse effects; D007089:Image Enhancement / Q000379:methods*; D017075:Laser Coagulation / Q000009:adverse effects* / Q000295:instrumentation; D008081:Liposomes; D011817:Rabbits; D012160:Retina / Q000293:injuries* / Q000528:radiation effects; D012680:Sensitivity and Specificity
D005452:Fluoresceins; D005456:Fluorescent Dyes; D008081:Liposomes; C024098:6-carboxyfluorescein