CILIARY BODY PDT IN
PIGMENTED RABBITS EYES: EFFECT OF SINGLE AND REPEATED TREATMENT.
M K Tsilimbaris, M Daskalakis, T L Naoumidi,
I I Naoumidi and I G Pallikaris
Vardinoyannion Eye Institute,University of
Crete Medical School,Greece
Abstract
We investigated the hypotensive effect of ciliary body PDT in the eyes of 30 pigmented
rabbits after single (n=25) and repeated (n=5) treatment. We used chloroaluminum
sulfonated phthalocyanine as photosensitizer and a diode laser (670 nm) as the light
source. Photosensitizer was administered by means of continuous intravenous infusion so as
to achieve stable plasma levels during PDT. Ciliary body was irradiated transsclerally by
means of an optic fiber applied on the corneoscleral limbus. In all cases 14 - 16 laser
applications were performed to cover 360° of the ciliary body. Animals were followed for
a maximum of 30 days by means of tonometry and biomicroscopy. Re treatments were performed
on day 13 using the same irradiation protocol. At the end of the follow up time animals
were sacrificed and their eyes prepared for light and electron microscopy. Transscleral
ciliary body PDT resulted in significant but temporary reduction of IOP in all cases. The
effect lasted about two weeks. Re treatment led to a new significant drop of the IOP which
lasted about two weeks again. In histological examination the initial effect of PDT was
vascular thrombosis which was followed by significant alteration at the level of ciliary
epithelium. Edema and disintegration of the ciliary epithelial layers were characteristic
findings the first days after treatment. All changes, however were temporary; after 15
days the appearance of the ciliary body had returned to normal both in single treated and
retreated animals. Contact transscleral PDT with the treatment parameters used in this
study results in significant but temporary functional and morphological alteration in
pigmented rabbits ciliary body. Further investigation may lead to a new PDT mediated
cyclodestructive technique with possible clinical applications in glaucoma treatment.
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