title: Noninvasive technique for monitoring chorioretinal temperature during transpupillary thermotherapy, with a thermosensitive liposome.
abstract: OBJECTIVE
  To develop a technique for noninvasive and real-time monitoring of chorioretinal temperature in transpupillary thermotherapy (TTT).
  
  
  METHODS
  A modified slit lamp, which was equipped with two laser wavelengths (490 nm for illumination and fluorescein excitation and 810 nm for hyperthermia), was developed for TTT and temperature monitoring. Five types of liposomes were prepared, and their phase-transition temperatures were 40 degrees C, 46 degrees C, 47 degrees C, 48 degrees C, and 52 degrees C, respectively. Carboxyfluorescein was encapsulated in each liposome. After intravenous injection of each liposome, TTT with the modified slit lamp was performed on normal rat choroid or tissue with choroidal neovascularization (CNV). During TTT, chorioretinal temperature was monitored by observing release of fluorescein from circulating liposomes.
  
  
  RESULTS
  Fluorescence from liposomes was initially observed around the heated lesion immediately after TTT began and disappeared rapidly when irradiation stopped. Choroidal and retinal temperatures were monitored separately. TTT for normal retina required higher power than that for normal choroid to observe fluorescence from a 40 degrees C, 46 degrees C, and 47 degrees C liposome. Retinal whitening was observed after TTT at a high-power setting. TTT for CNV required higher laser power than that for the normal choroid and retina.
  
  
  CONCLUSIONS
  The results demonstrate the potential use of a noninvasive monitoring technique of chorioretinal temperature during TTT. The method should be useful to establish the TTT setting and achieve the optimal temperature increase in CNV.
authors.affiliation: Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Miura
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Nishiwaki
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Ieki
authors.forename: Yuya
authors.initials: Y
authors.lastname: Hirata
authors.forename: Junichi
authors.initials: J
authors.lastname: Kiryu
authors.forename: Yoshihito
authors.initials: Y
authors.lastname: Honda
mesh_terms: D000818:Animals; D001831:Body Temperature; D002829:Choroid / Q000502:physiology* / Q000528:radiation effects; D020256:Choroidal Neovascularization / Q000503:physiopathology / Q000628:therapy*; D004195:Disease Models, Animal; D005452:Fluoresceins / Q000008:administration & dosage*; D005453:Fluorescence; D006979:Hyperthermia, Induced; D007275:Injections, Intravenous; D008081:Liposomes; D008297:Male; D008991:Monitoring, Physiologic / Q000379:methods*; D011680:Pupil; D011833:Radiation Injuries, Experimental / Q000517:prevention & control; D051381:Rats; D020318:Rats, Long-Evans; D012160:Retina / Q000502:physiology* / Q000528:radiation effects
chemical_list: D005452:Fluoresceins; D008081:Liposomes; C024098:6-carboxyfluorescein