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JA Burke, T Lin, W Ho, G DeVries, L Wheeler; Time Course of Retinal Edema Following Verteporfin Photodynamic Therapy (PDT) in Pigmented Rabbits: An Optical Coherence Tomography (OCT), Color Funduscopy and NaF Angiography Study . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2824.
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Purpose:To investigate the effects of verteporfin PDT on retinal mophology in the normal rabbit. Methods:Conscious pigmented rabbits were given an iv infusion of 10 mls (1 ml/min) verteporfin 0.2 mg/kg (equivalent to clinical dose by body weight) via the marginal ear vein. Animals were dilated with phenyephrine and tropicamide, anesthetized with iv ketamine and acepromazine, and irradiated in the lower fundus with a 689 nm diode laser at 50 J/cm2, 600 mW/cm2 according to the following study designs. Study #1: Single 5 mm spot 3 minutes post-verteporfin. Follow-up measurements (color funduscopy and NaF angiography with a Zeiss FF 450 IR fundus camera and OCT with a Zeiss Humphrey OCTII system) were made on Days 1, 2, 4, 7, 9, 11, 14, 16 and 18. Study #2: Two 1.5 mm spots at 10 and 15 minutes post-PDT placed 6 mm apart. Follow-up measurements as above were made at 4 hours, and Days 1, 2, 3 and 4 post-PDT. Results:Study 1: Retinal thickness (RPE - ILM) was maximal on Day 4: 524 10 um including a subretinal cyst of 292 17 um (normal thickness = 156 1.4 um) which resolved by Day 7. Retinal thickness was significantly elevated up to Day 9. Maximum area of NaF hypofluorescence within the PDT lesion occurred at Day 4 (16 1 mm2 out of a possible 19.6 mm2 compared to hypofluorescence area in untreated retina of 0.17 0.1 mm2). Study #2: Retinal thickness in the 10-minute lesion was greater than in the 15-minute lesion up to Day 2. The peak difference occurred at Day 1; retinal thickness for the 10-minute lesion was 257 6 um (including a subretinal cyst of 76.4 5.3 um) and for the 15-minute lesion was 196 9 um. Hypofluorescence in these smaller (1.5 mm) lesions was obscured by the edema which spread beyond the borders of the treatment area in the 10-minute lesion; color funduscopy showed that edema area increased up to Day 3; maximum increase was 13.6 0.9 mm2 @ Day 2. Conclusion:Verteporfin PDT produces edema, which increases retinal thickness, including subretinal cysts, in the normal rabbit fundus. These effects were transient, resolving in just over a week.
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