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PENG QIN, Ian Wong; The effect of varying dosage and fluence setting of Verteporfin on choroidal vasculature in a rodent model. Invest. Ophthalmol. Vis. Sci. 2019;60(9):371.
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© ARVO (1962-2015); The Authors (2016-present)
Polypoidal choroidal vasculopathy(PCV) is a prevalent type of subretinal neovascularization in Asian populations. Photodynamic therapy (PDT) using the photosensitizing dye Verteporfin is one of the current treatments of choice for subfoveal choroidal neovascularization (CNV). However, preclinical and clinical studies demonstrate that PDT is not perfectly selective for CNV. Although PDT preferentially affects pathologic vessels, it can also cause collateral damage to the surrounding choroidal vessels. Recent studies have shown that polyps regression rate after half-dose PDT combined with intravitreal ranibizumab was similar to that of standard-dose PDT, particularly for those patients with one single polyp lesion. This study aimed to compare the toxicity profile of half-dose PDT with the standard-dose PDT to choroidal vasculature.
SD rats that accepted sham PDT and standard-dose PDT(Verteporfin 6mg/m2, laser power 50 J/cm2) were used as negative and positive controls, respectively. Half-dose PDTs with either half dosage of Verteporfin(3mg/m2) or half laser power(25 J/cm2) were applied to the age-matched rats. 24hours after PDT, vascular oxidative stress was examined on choroidal wholemounts by co-staining Isolectin(endothelium) with Dihydroethidium(superoxide). Number of subretinal hemorrhage was also observed among the varying-dose PDT groups. As choroidal ischemia might result in retina dysfunction, scotopic ERG was investigated. Statistical analyses were performed using One-way ANOVA followed by Bonferroni-Dunn test.
Standard-dose treated rats(n=8) showed decreased amplitude of a-wave in scotopic ERG(p<0.05) as well as increased intensity of vascular oxidative stress(p<0.01) at the site of laser application. Rats(n=8) in half dose of Verteporfin(3mg/m2) group exhibited amelioration of retinal dysfunction and less superoxide staining in choroidal vasculature(p<0.01). However, rats(n=8) in half laser power(25 J/cm2) group only showed a minor but not significant attenuation of vascular oxidative stress and retinal dysfunction. Two cases of subretinal hemorrhage were observed in standard-dose treated rats, whereas no case was found in either half-dose treated rats.
PDT with half dose of Verteporfin but not half laser power was less toxic to normal choroidal vasculature, suggesting a promising use in PCV treatments, particularly for small polyps lesion.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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