| ObjectiveThe process of submacular angiogenesis seen in association with a variety of chorioretinal disorders is termed choroidal neovascularization (CNV). Among these diseases AMD is the most common, and a similar process occurs in what is clinically termed CNV. Angiogenesis is just one component of this wound healing process. Other key components include inflammation, matrix deposition and remodeling. Thus, in the context of a tissue repair response, viable treatment options for CNV could include therapies other than those that are currently directed at the angiogenic component of this process.The purpose of this study: To evaluate the feasibility of krypton laser-induced CNV model in the pigmented rabbits in order to establish the foundation for studying the mechanism of CNV and for the development of treatment for CNV. At a given time, to determine the effects of intravitreal triamcinolone acetonide(TA) on the experimental CNV of rabbit. To observe the safety of TA by histological examination. Methods1. Study on the model of Krypton Laser-induced CNV in the rabbitExperimental eyes in 14 rabbits were received a series of 25 krypton redlaser lesions per eye. Krypton laser was applied to the fundus under the following conditions: wavelength 647 run, power 380~400mw, spot size 50 um, exposure time 0.05 senconds. Fundus fluorescein angiography (FFA) and fundus photography were performed on days 7, 14, 21, 28, 56 and 84. Eyes were enucleated on days 3, 7, 14, 21, 28, 56 and 84 after laser, fixed in acid formalin and embedded in paraffin. Histological examination by light microscopy was performed on hematoxylin-eosin (HE) stained paraffin embedded sections.2. Effects of Intravitreal TA on the CNV of Rabbit Twelve anaesthetised rabbits received a series of 25 krypton red laser lesions per eye. Total 24 eyes of 12 rabbits were randomly divided in 4 groups which included group A, B, C and D. Six right eyes of 6 rabbits were randomly divided into group A, and the left eyes were in group B. The remaining six right eyes were in group C, and the left eyes were in group D. The eyes in group A received an intravitreal injection of TA (4mg, 0.1ml) after the laser immediately. The eyes in group B received an injection of isotonic sodium chloride solution(0.1 ml) after the laser immediately. The eyes in group C received an intravitreal injection of TA (4mg, 0.1 ml) on days 14 after the laser. The eyes in group D received an injection of isotonic sodium chloride solution(0.1 ml) on days 14 after the laser.After intravitreal injection, we observed the fundus with ophthalmoscope on days 1, 7, 14, 21, 28 and 35. Intravitreal injection 14 days and 35 days later, the animals were sacrificed to observe the anterior chamber, lens, vitreous, retina and choroids of the rabbits by histological examination. The thickness of the experimental FVP from the retinal pigment epithelium was measured. Serial histological specimens were methodically assessed in a masked fashion to analyze each laser lesion for the FVP; maximum FVPthickness for each lesion was measured from the retinal pigment epithelium. Results1. Study on the model of Krypton Laser-induced CNV in the rabbit Histologically, CNV represented a stereotypic and nonspecific woundrepair response. It was firstly observed on days 14 after photocoagulation by FFA and light microscopy, reaching the peak on days 21. Then it gradually involuted and became scar. CNV was ascertained by light microscopy. Disciform or feathery leakage staining appeared in the FFA. The rate of leakage in the FFA was 40%, 60%, 68%, 56% on days 14, 21, 28 and 56 respectively.2. Effects of Intravitreal TA on the CNV of RabbitIn treated eyes the development of CNV was significantly inhibited. Histologically, the FVP membrane was observed beneath the retina, and the thickness of the lesions was reduced significantly(P< 0.01) in the treated eyes. On days 14 after intravitreal injection, the mean thickness of the recovered lesions (n = 20) was measured, and the results was 40.02 + 2.48 um in group A, 45.64 +1.99 um in group B, 39.78±1.96 jam in group C, and 38.86±3.47 um in group D. On days 35 after intravitreal injection, the mean thickness of the recovered lesions (n=20) was measured, and the results was 30.57 + 2.88 um in group A, 33.91±1.96um in group B, 44.59±2.39 um in group C, and 43.54±2.48 um in group D. There was a statistical difference in the thickness of the CNV lesions respectively between group A and group B, and group C and group D. There was no histological change of retina without laser-treated and lens after intravitreal injection of TA. Conclusions1 .The present studies demonstrated that krypton laser photocoagulation could be successfully used to produce experimental CNV model in the...
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