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T. L. Gosen, R. Mandiga, A. A. Polinkovsky, A. D. Rolin, S. S. Huang; An ex-vivo Model for Anterior-Posterior Ocular Injury - Implications for the Vitreo-Retinal Interface. Invest. Ophthalmol. Vis. Sci. 2009;50(13):3187.
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To construct a reliable and reproducible model for anterior-posterior deceleration injury in porcine and bovine globes for further investigation of vitreo-retinal interface (VRI) injury.
A linear track was utilized to minimize extraneous forces applied to the eye. An accelerometer on the housing measured the acceleration of the eye. Bovine and porcine globes obtained within 48 hours of enucleation were secured in a padded housing with nylon and cyanoacrylate at the points of rectus muscle attachment. The theoretical impact velocity given negligible friction and linear deceleration was calculated with the equation Vi=(2gh)1/2 where h=length of track, g=acceleration due to gravity (9.8 m/s2), giving an impact deceleration ai=Vi/t where ti=time of impact. Test globes were released from h=1.65m in a vertical vector, and then inspected for VRI injury.
The theoretical velocity on impact was 5.687 m/s (12.72 mph). Porcine eye mean ti=4.352 ms (range 3.300-5.584 ms; n=12) and for bovine eyes was 5.170ms (range 3.720-6.080 ms; n=8). Porcine eye mean ai=126.361g (range 100.050-175.845 g; n=12) and bovine eye mean ai=115.031g (range 95.442-155.992g; n=8). This deceleration is 3-4 times greater than the deceleration for irreversible brain damage, 30g. VRI injury in the form of retinal tear, retinal dialysis, retinal detachment, avulsion of the vitreous base, and/or RPE pigment changes was found in 12 of 12 porcine and 8 of 10 bovine eyes.
An analysis of physical factors defining ocular injury to the VRI from traumatic anterior-posterior deceleration has not been previously published. This model provides a platform for clinicopathologic study for ocular head-on deceleration injury. Gross pathology suggests that this model will yield definable parameters for threshold VRI injury in a head-on collision. From NTSB research, it is known that impact time plays a disproportionate role in deceleration injury. Multivariate changes to the model will be conducted to further refine physical characteristics leading to injury and to simulate clinical scenarios.
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