Transpupillary thermotherapy: effect of wavelength on normal primate retina.
OBJECTIVE
To correlate changes in primate fundus after transpupillary thermotherapy (TTT) at two wavelengths.


METHODS
Twelve primate eyes were treated with TTT using a wavelength of 635 nm (n=7) or 810 nm (n=5). Laser parameters were as follows: 635 nm (spot size, 1 mm; duration, 30-8 seconds; and fluence [power over time], 20-91.4 J/cm) and 810 nm (spot size, 2 mm; duration, 60 seconds; and fluence, 96-436 J/cm). Fundus photography, fluorescein and indocyanine green angiography, and enucleation were performed at time 0 or 2 weeks after TTT for histologic analysis.


RESULTS
Threshold for fundus lesions (91.4 J/cm at 635 nm and 191 J/cm at 810 nm), acute and chronic retinal damage shown by histologic analysis (79.2 J/cm at 635 nm and 96 J/cm at 810 nm), and choroidal vessel occlusion (50 J/cm at 635 nm and 96 J/cm at 810 nm) were lower at 635 nm. Disorganization of the retina and retinal pigment epithelium was seen for both wavelengths at time 0 and 2 weeks after TTT. Occlusion of the choriocapillaris and choroidal stromal vessels was noted only in specimens obtained 2 weeks after TTT.


CONCLUSIONS
TTT resulted in acute and delayed damage to the neurosensory retina that persisted at 2 weeks. The 635-nm wavelength demonstrated a lower threshold fluence for visible fundus lesions, retinal damage, and choroidal vascular occlusion than the 810-nm laser.
Ito
Yoko
Y
Department of Ophthalmology, Saitama Medical School, Saitama, Japan.
Mori
Keisuke
K
Takita
Hiroyasu
H
Sodeyama
Takeo
T
Anzai
Kaname
K
Imai
Daisuke
D
Shibuya
Masayuki
M
Moshfeghi
Darius M
DM
Yoneya
Shin
S
Peyman
Gholam A
GA
D000818:Animals; D001808:Blood Vessels / Q000648:ultrastructure; D002829:Choroid / Q000098:blood supply; D005131:Eye Injuries / Q000209:etiology* / Q000473:pathology; D005451:Fluorescein Angiography; D006979:Hyperthermia, Induced / Q000295:instrumentation*; D007208:Indocyanine Green; D007834:Lasers / Q000009:adverse effects*; D008251:Macaca; D023421:Models, Animal; D010857:Pigment Epithelium of Eye / Q000293:injuries* / Q000648:ultrastructure; D011680:Pupil; D012160:Retina / Q000293:injuries* / Q000648:ultrastructure; D012684:Sensory Thresholds
D007208:Indocyanine Green