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R. Mandiga, T. L. Gosen, S. S. Huang; Vitreo-Retinal Interface (VRI) Injury After Acceleration Impulse in a Porcine Model. Invest. Ophthalmol. Vis. Sci. 2010;51(13):1889.
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To identify a threshold for VRI injury after anterior-posterior (A-P) and lateral vector acceleration impulse in a fresh porcine globe model.
Fresh porcine globes were shipped overnight from Sioux-Preme Packaging (Sioux City, IA) on ice within 24 hours of harvest. As per our protocol to generate a model that mimicked human adult vitreous, each eye was injected with 0.3cc of 0.25% trypsin-EDTA (Invitrogen Carlsbad, CA) and incubated for 2 hours. A pendulum induced A-P or lateral vector acceleration impulse on each globe suspended within a housing box attached to an Endevco 751-10 accelerometer (San Juan Capistrano, CA) to generate impulses of 60g, 100g, 200g, 300g, 400g, and 500g. Each globe was dissected and inspected for gross VRI injury.
In the A-P vector group, 10% of the eyes at 60g (n=10), 20% at 100g (n=10), 60% at 200g (n=10), 54.5% at 300g (n=11), 80% at 400g (n=15) and 90% at 500g eyes (n=20) showed VRI injury. Under 400g, VRI injury was limited to 1 quadrant of up to 3 holes at the vitreous base. Above 400g, VRI injury included up to 5 holes, small horseshoe tears, or dialyses in one quadrant of the vitreous base. In the lateral vector group, 10% of the eyes at 60g (n=10), 40% at 100g (n=10), 60% at 200g (n=10), 70% at 300g (n=10), 90% at 400g (n=10) and 90% at 500g (n=10) showed VRI injury. Under 400g, VRI injury included up to 5 holes or multiple tears in multiple quadrants of the vitreous base. Above 400g, VRI injury was extensive from 4 to 16 holes, multiple dialyses, and horseshoe tears located around the vitreous base.
The threshold for VRI injury lies between 60g and 100g after both A-P and lateral vector acceleration impulse injury and was localized to the vitreous base in our model. The injury pattern varied by impulse vector. A-P impulse consistently produced single quadrant relatively minor VRI injury, while lateral impulse produced more extensive multiple quadrant injury regardless of amplitude. A proposed explanation for more extensive injury in the lateral group is that the eye is better equipped to handle the shearing A-P vector impulse by benefiting from a firm attachment of the vitreous base to the optic nerve head and retinal vessels and a buffering effect of the lens-iris diaphragm.
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