Abstract
Abstract: :
Purpose:To evaluate the effects of Verteporfin PDT on retinal function in the normal rat. Methods:Brown Norway rats weighing 250-300 grams were used. Animals were anesthetized with 12 mg /100 g tribromoethanol ip for each procedure. Verteporfin PDT: A bolus injection of verteporfin was administered into a cannulated femoral vein at 0.2 mg/kg (equivalent to the clinical dose by body weight). Five minutes following dye administration, the right eye was irradiated with a 689 nm diode laser at 50 J/cm2, 600 mW/cm2 and a spot size of 4 mm (at the cornea) centered on the optic nerve head. ERG: Rats were dark-adapted for 15 minutes, connected to bilateral cornea electrodes and stimulated using a LKC Ganzfeld electrophysiology system, and followed-up (FU) at 4 hours, and Days 1, 2 and 5 post-PDT. OCT: Horizontal scans were made across the optic nerve and retinal thickness measurements were assessed on either side of the nerve head and averaged using a Zeiss Humphrey OCT II system; FU was at 4 hours, and Days 2 and 6 post-PDT. NaF angiography: A Zeiss FF 450 IR fundus camera was used to image the retina following an iv injection of 0.2ml of 1% NaF; FU was at 4 hours, and Days 2 and 6 post-PDT. Results:At 4 hours post-PDT, verteporfin reduced ERG A-wave and B-wave amplitudes 20 ± 9% and 25 ± 6%, respectively. Peak responses were at Day 1: A and B-waves were reduced 23 ± 9% and 41 ± 4%, respectively. At Day 5, responses were still reduced ∼ 20%. Retinal thickness increased 25 ± 3%, 13 ± 5% and 4 ± 2% at 4 hours, Days 2 and 6, respectively. NaF angiography showed occlusion of choroid only; retinal vessels remained open. Analysis showed that out of a possible maximum of 12.6 mm2, the hypofluorescence areas were 6.8 ± 1, 7.7 ± 0.2 and 7.4 ± 0.7 mm2 at 4 hours, Days 2 and 6, respectively (normal = 2.7 ± 0.7 mm2). Conclusion:Verteporfin PDT produced transient edema and persistent choroidal occlusion and ERG deficits in the normal rat retina.
Keywords: 516 photodynamic therapy • 316 animal model • 432 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)