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C.K. Spee, K. Fujisawa, J. Oh, L. Liu, P. Margaron, D.R. Hinton; Impact of Triamcinolone on High Doses of PDT in the Rabbit Chorioretina . Invest. Ophthalmol. Vis. Sci. 2003;44(13):5006.
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Purpose: Inflammation of the choroid has been associated with neovascularization and may play a role in the reappearance of leakage after photodynamic therapy (PDT) with verteporfin (Visudyne®; Novartis AG). This in vivo study was conducted to assess the effect of the anti-inflammatory agent triamcinolone acetonide (TA) on the inflammatory response of choroidal tissues to PDT. Methods: Nine rabbits were divided into three groups of three animals each: · Group 1: PDT with verteporfin (2 mg/kg i.v. bolus) and 75, 100, and 150 J/cm2 of red light (three 1.25-mm diameter spots in one eye, with the collateral eye as a control) applied 15, 20, and 25 min after verteporfin injection, respectively. These doses of PDT were selected based on their ability to evoke a sustained inflammatory response in the chorioretina. · Group 2: PDT as above + intravitreal injection of TA (4 mg in 0.1 mL of saline solution) · Group 3: PDT as above + intravitreal injection of saline solution (0.1 mL) Fundus photographs and fluorescein angiograms were obtained over the course of the 28-day experiment. After the animals were euthanized, frozen sections of eye tissue were prepared and immunohistochemical analysis was performed to evaluate the extent of inflammation in retinal and choroidal tissue. Results: PDT induced moderate degeneration of the retina with loss of photoreceptors, mild to moderate RPE loss in the center of the lesion and focal RPE proliferation at the periphery. Increased numbers of macrophages and CD4 cells and rare CD8 cells were seen at the site of the PDT lesion in the retino-choroidal tissue. The inflammatory cells showed increased expression of MHC class II antigen. The three PDT regimens evoked a similar response in the chorioretina. Eyes treated with triamcinolone after PDT was found to have substantially fewer inflammatory cells, especially macrophages. These tissues also contained fewer proliferating RPE cells. Examination of the photographic and histological material showed reduced pigmentation in the laser spots of eyes treated with TA. Conclusions: These results support the use of intravitreal TA as an anti-inflammatory adjunct to PDT with verteporfin, while the impact of the combined therapy on RPE and fundus pigmentation remains unclear.
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