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A. M. Alegret, A. C. Schefler, Y. Pina, H. Boutrid, E. Hernandez, M. Ruggeri, S. Jiao, T. G. Murray; Recent Advancements in 532 Green Laser Technology and Probe Enhancement: Clinical Assessment and Laboratory Evaluation. Invest. Ophthalmol. Vis. Sci. 2009;50(13):2082.
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The endolaser is a highly critical component of vitreoretinal surgery. To investigate the anatomic effects of 532 nm thin disk laser - pan focal endolaser photocoagulation was performed using a range of laser power settings and pulse durations in a Dutch-belted rabbit with a moderately pigmented fundus.
This study was approved by the IACUC and follows ARVO guidelines. A focal endolaser photocoagulation using a range of laser power settings was performed. Laser was delivered in a 5 x 5 treatment box with laser parameters at clinically relevant settings and varying pulse duration and power. Pulse duration was varied from 0.1 to 0.8 ms with fixed power, while power was varied from 200 to 100 mw with fixed pulse duration establishing the treatment box. Three days later, Fundus and Spectral Domain Optical Coherence Tomography (OCT) Imaging was performed. Eyes were enucleated, placed in OCT, snap frozen in liquid nitrogen, and sectioned. Twenty-four sections taken at even intervals to sample the entire globe were stained with hematoxylin-eosin (H&E).
Fundus photographs demonstrated full thickness retinal burns with surrounding RPE atrophy. OCT demonstrated full-thickness retinal atrophy and scarring. The width of the chorioretinal scars varied based on the power setting at which the laser was set; high powered burns produced wider scars. Compared with the normal retinal architecture, there is progressive retinal necrosis and edema with increasing amounts of laser power used. OCT imaging showed that the width of the retinal damage was greater with higher powered burns.
Our work in the laboratory documents that the laser produces rapid, effective thermal burns. The precision of laser application suggests that retinal/choroidal targeting is a function of energy transfer and laser modulated by pulse duration and power application.
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