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Brittany A. Jackson, Richard L. Ornberg; Implementation of Spectral Domain Optical Coherence Tomography for Post Laser Verification of Thermal Laser Induced Choroidal Neovascularization in the Primate Model. Invest. Ophthalmol. Vis. Sci. 2012;53(14):3015.
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Focal thermal laser ablation to the peri-macular retina is a common method for creating choroidal neovascular (CNV) lesions for evaluating therapeutics for age related macular degeneration (AMD). To date, a variety of laser parameters and evaluation methods used have resulted in CNV development in less than 50% of laser burns delivered. In this study, SDOCT was used to objectively assess Bruch’s membrane rupture immediately post laser against a range of commonly used thermal laser parameters. The SDOCT findings were then correlated with the creation of leaky CNV lesions in a primate model of AMD
Naïve Cynomolgus monkeys (n=3, 2.4-5.8kg) were sedated and given topical mydriatics and anesthetic to effect for the bilateral laser procedure. Using the Novus Varia three mode laser system, thermal laser lesions were induced using argon green (532nm, 0.1 sec, 50um) with power set at 350, 550, 750 or 900 mW) or krypton red (657nm, 600mW, 0.1sec.) with spot size set 50 or 75um to examine a single eye with 6 spots per treatment condition. SDOCT was acquired for each lesion in a 6-burn pattern around the fovea immediately post laser. Fluorescein angiography, color funduscopy and SDOCT were performed biweekly through 6 weeks post procedure to document CNV leakage and vascular network formation.
The majority of argon green laser settings did not rupture Bruch’s membrane when viewed with SDOCT, and indeed did not produce clinically relevant CNV lesions. SDOCT verification of Bruch’s membrane rupture was observed for 5 of 6 of the laser lesions made with 657nm at 75um spot size, with 6 of 6 CNV showing leak to 6 weeks. Only 3 of 6 laser lesions made with argon green at750mW power appeared to have ruptured Bruch’s membrane. Of these, 6 of 6 lesions demonstrated leaked through 4 weeks but only the 3 the lesions with a ruptured Bruch’s membrane were leaky at 6 weeks post laser
SDOCT examination of Bruch’s membrane rupture following laser treatment is more reliable than a subjective assessment of thermal laser burns as a predictor of CNV development. Lesions produced by krypton red excitation at 75um spot size produced a higher percentage of CNV compared to those produced by the range of power settings for argon green
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