T. Schlote et al., Alteration of the vascular supply in the rabbit ciliary body by transscleral diode laser cyclophotocoagulation, GR ARCH CL, 239(1), 2001, pp. 53-58
Citations number
29
Categorie Soggetti
Optalmology
Journal title
GRAEFES ARCHIVE FOR CLINICAL AND EXPERIMENTAL OPHTHALMOLOGY
Background: Besides the direct destruction of the non-pigmented ciliary epi
thelium by cyclodestructive procedures, further mechanisms are responsible
for the decrease of intraocular pressure. This study evaluates the alterati
on of the ciliary body vascularization by contact transscleral diode laser
cyclophotocoagulation in rabbit eyes. Methods: Pigmented chinchilla bastard
rabbits were used. Preliminary experiments were conducted to determine the
parameters for diode laser cyclophotocoagulation of the pars plana or pars
plicata. Then, treatment of the pars plicata (three rabbits) or pars plana
(three rabbits) was performed in the right eye of six rabbits. After 2, 6
and 12 weeks histologic and transmission electron microscopic studies were
performed. Furthermore, three rabbits received pars plicata cyclophotocoagu
lation of the right and pars plana cyclophotocoagulation of the left eye. A
fter 2, 6 and 12 weeks, vascular casts of the ciliary body were investigate
d by scanning electron microscopy. Results: Histologic and transmission ele
ctron microscopic studies showed a marked coagulation necrosis with subsequ
ent ciliary body atrophy, destruction of the ciliary epithelium, pigment di
spersion in the ciliary body stroma and peripheral anterior synechiae. Exam
ination of vascular casts of the ciliary body revealed a marked rareficatio
n of the capillary network within the treated areas of the ciliary body in
all eyes and at every time of investigation. Anterior to the laser bums the
capillary network was not markedly affected in the eyes with cyclophotocoa
gulation of the pars plana. After 3 months short vessel sprouts were seen,
but regeneration was mostly incomplete. Conclusions: The vascular casting t
echnique is an excellent method for the investigation of changes in ciliary
body vascularization after cyclodestruction. This study is the first to de
monstrate a marked rarefication of the ciliary body vascularization after d
iode laser cyclophotocoagulation using vascular casts. The results suggest
that alteration of vascularization probably acts as a strong synergistic me
chanism in the decrease of intraocular pressure after cyclophotocoagulation
of the pars plicata.