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Xiaorong Liu, Liang Feng, Ishan Shindi, John B Troy, Laxman Saggere; Correlation between RGC loss and optic nerve crush force impulse in mice established with an instrumented forceps. Invest. Ophthalmol. Vis. Sci. 2019;60(9):676. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Rodent models of optic nerve crush have often been used to study degeneration and regeneration of RGCs and their axons as well as the underlying molecular mechanisms. However, results from different laboratories exhibited a diverse range of RGC damage which lacks consistency, reliability and a means for quantification of the degree of axonal damage. Therefore, in this study, we examined the correlation between the RGC axon loss and the product of force and duration delivered by a self-closing Dumont forceps.
We integrated standard self-closing #N7 tweezers with miniature foil strain gauges. The instrumented tweezers were capable of recording the tip closure forces in the form of voltages, which were calibrated through load cells to corresponding tip closure forces over the operating range. The sensors were mounted at optimal locations on both arms of the tweezers to maximize the force sensitivity recorded by the tweezers. Optic nerves crushed with the instrumented tweezers were dissected and prepared for immunostaining for axon counting.
We crushed the optic nerves of multiple mice with varied forces and durations, and then plotted surviving axon density versus the crush forceimpulse. As expected, we found that longer duration and stronger crush forces produce more axon damage (see Figure).
The data and knowledge gathered from this study will serve as baseline inputs to the design and development of a new instrument to induce consistent damage to the optic nerve with controlled force, duration, and location.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
Axon loss correlates with the product of force (Newtons) and duration (seconds). Inset: The Dumont #N7 tweezers instrumented with a thin-foil strain gauge sensor.
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