Neovascularization in the anterior segment of the rabbit eye by experimental anterior ischemia.
OBJECTIVE
To investigate the effects of anterior ischemia accompanied by neither retinal nor choroidal ischemia on the anterior segment of the eye.


METHODS
Both long posterior ciliary arteries in the right eye of 14 rabbits were directly cauterized with an electric coagulator. The eyes were enucleated 1, 2, 4, 7, 9 or 14 days after cauterization, then fixed with 4% paraformaldehyde. Semi-thin sections were studied by light microscopy. Several sections were stained with Griffonia simplicifolia lectin, which bound specifically to mammalian vascular endothelium. Other specimens were examined immunohistochemically for vascular endothelial growth factor (VEGF) protein. The tissue specimens of the first postoperative day were studied for expression of VEGF mRNA by in situ hybridization.


RESULTS
Atrophy of the iris and ciliary body was seen after the second postoperative day. Corneal neovascularization appeared after 7 days. Neovascularization on the anterior surface of the iris and in the trabecular meshwork was detected after the ninth postoperative day. The proliferative tissues with newly formed vessels obstructed the iridocorneal angle 14 days after the treatment. There was no histological change in either the retina or choroid. Immunohistochemically, VEGF protein was detected in the epithelial and vascular cells of the iris on the first and fourth postoperative day. Expression of VEGF mRNA was detected in the epithelial cells of the ciliary body on the day following the treatment.


CONCLUSIONS
Anterior segment ischemia, when unaccompanied by retinal ischemia, causes neovascularization in the cornea, iris and trabecular tissue.
Tawara
Akihiko
A
Department of Ophthalmology, University of Occupational and Environmental Health, Japan. tawara-a@med.uoeh-u.ac.jp
Kubota
Toshiaki
T
Hata
Yasuaki
Y
Sakamoto
Taiji
T
Honda
Masae
M
Yoshikawa
Hiroshi
H
Inomata
Hajime
H
Ohnishi
Yoshitaka
Y
D000818:Animals; D000869:Anterior Eye Segment / Q000098:blood supply* / Q000473:pathology; D001284:Atrophy / Q000473:pathology; D015153:Blotting, Western; D019842:Ciliary Arteries / Q000601:surgery; D002924:Ciliary Body / Q000098:blood supply / Q000473:pathology; D004564:Electrocoagulation; D016228:Endothelial Growth Factors / Q000235:genetics / Q000378:metabolism; D004730:Endothelium, Vascular / Q000378:metabolism / Q000473:pathology; D007124:Immunoenzyme Techniques; D017403:In Situ Hybridization; D007498:Iris / Q000098:blood supply / Q000473:pathology; D007511:Ischemia / Q000150:complications*; D008222:Lymphokines / Q000235:genetics / Q000378:metabolism; D009389:Neovascularization, Pathologic / Q000209:etiology* / Q000473:pathology; D012333:RNA, Messenger / Q000378:metabolism; D011817:Rabbits; D014129:Trabecular Meshwork / Q000098:blood supply / Q000473:pathology; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
D016228:Endothelial Growth Factors; D008222:Lymphokines; D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors