Inhibition of preretinal and optic nerve head neovascularization in pigs by intravitreal triamcinolone acetonide.
OBJECTIVE
The authors tested the antiangiogenic properties of intravitreally administered triamcionolone acetonide in a pig model of preretinal neovascularization to determine the effectiveness of this therapy in preventing neovascularization.


METHODS
In 14 eyes of seven pigs, branch retinal vein occlusions were created in a standardized manner using photodynamic thrombosis with rose bengal dye and thermal burns from the argon green laser. Intravitreal injection of approximately 4 mg of triamcinolone acetonide was performed in one eye of each animal, and eyes were followed clinically for 12 weeks with ophthalmoscopy and fundus photography. A standardized grading system was developed to permit masked assessment of disc proliferations from fundus stereophotographs. After death, all neovascularization was confirmed histopathologically and a final grade was assigned to each eye. Statistical analysis employed use of a nonparametric test of the paired data.


RESULTS
Significant inhibition of neovascularization was observed in triamcinolone-treated eyes (P = 0.0156). Although none of the steroid-injected eyes demonstrated clinically evident new vessels, histopathologic and photographic analysis results demonstrated fine new vessels on the optic disc in four eyes. In all of the untreated eyes, neovascularization of a moderate (II) to high (III to IV) grade developed.


CONCLUSIONS
Intravitreal triamcinolone acetonide effectively inhibited preretinal and optic nerve head neovascularization in the pig model. The grading system used permitted masked assessment of outcome and paired analysis allowed a conclusion to be drawn from a relatively small number of eyes. The mechanisms by which triamcinolone acetonide inhibits neovascularization remain to be elucidated.
Danis
R P
RP
Department of Ophthalmology, Indiana University Medical School, Indianapolis 46202-5175, USA.
Bingaman
D P
DP
Yang
Y
Y
Ladd
B
B
D000818:Animals; D004195:Disease Models, Animal; D005938:Glucocorticoids / Q000008:administration & dosage / Q000627:therapeutic use*; D007267:Injections; D008297:Male; D009898:Optic Disk / Q000098:blood supply* / Q000473:pathology; D015861:Retinal Neovascularization / Q000188:drug therapy* / Q000209:etiology / Q000473:pathology; D012170:Retinal Vein Occlusion / Q000150:complications; D013552:Swine; D014222:Triamcinolone Acetonide / Q000008:administration & dosage / Q000627:therapeutic use*; D014822:Vitreous Body
D005938:Glucocorticoids; D014222:Triamcinolone Acetonide