Electron microscopic study of monkey retina after photodynamic treatment.
The purpose of this histological study was to determine the effects of photodynamic treatment, using a hematoporphyrin derivative and argon laser, on normal retinas of monkeys. Ten cynomolgus monkeys were treated with a hematoporphyrin derivative, given intravenously at a dose of 2.5 mg/kg. Forty minutes or 1 or 3 days after the injection, argon laser photoradiation was given over a 2.0-mm-diameter with a 10-min exposure and at an intensity of 40, 100, or 200 mW. The eyes were enucleated 1, 3, 4, 15, 18, 21, 35, or 38 days after the photoradiation and tissue samples were observed under a transmission electron microscope. The most fragile regions in the retina were the retinal nerve fibers, the outer segments of the visual cells, and the retinal pigment epithelium. Vascular endothelial cells were also fragile. The retinal capillary was easily obstructed, and the choriocapillaris was also occluded in an animal with severe retinal damage. The Mueller cells had the highest tolerance to the photodynamic treatment. Thus, exposing the normal part of the retina to light during photodynamic therapy should be avoided.
Department of Ophthalmology, Wakayama Medical University, Kimiidera 811-1, Wakayama 641-8509, Japan.
Yoshitaka
Y
Ohnishi
Takeshi
T
Yoshitomi
Toshinori
T
Murata
Taiji
T
Sakamoto
Tatsuro
T
Ishibashi
D000818:Animals; D017324:Hematoporphyrin Derivative / Q000009:adverse effects; D006801:Humans; D008252:Macaca fascicularis; D008854:Microscopy, Electron; D010778:Photochemotherapy / Q000009:adverse effects*; D017319:Photosensitizing Agents / Q000009:adverse effects; D012160:Retina / Q000187:drug effects / Q000293:injuries* / Q000528:radiation effects / Q000648:ultrastructure*
D017319:Photosensitizing Agents; D017324:Hematoporphyrin Derivative