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Ryan A. McClure, Ying Hu, Eleut Hernandez, William Lee, Fabrice Manns, John Guy, David Tse; Small Animal Laser-induced Focal Injury Model for Traumatic Optic Neuropathy. Invest. Ophthalmol. Vis. Sci. 2011;52(14):4673.
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© ARVO (1962-2015); The Authors (2016-present)
To develop an in vivo mouse model for Traumatic Optic Neuropathy (TON) using ab externo laser-induced acoustic transients to produce focal optic nerve lesions.
The optic nerve of four mice were surgically exposed and irradiated with a Q-switched Nd:YAG laser using two different delivery systems: 1) A custom-build free-space delivery system coupled to an operation microscope and 2) a commercial fiber-optic laser beam delivery system (Q-LAS, A.R.C. Laser, Nuremberg, Germany). The free-space system uses a Q-switched Nd:YAG laser (8ns pulse duration, Brilliant 50, Quantel, Les Ulis, France) in combination with a green aiming beam. The Nd:YAG laser beam is focused in the focal plane of the operation microscope into a 50µm diameter spot to produce a direct photoacoustic effect on the optic nerve. The A.R.C Q-LAS delivers the treatment beam through a special contact fiber optic probe containing a titanium target. Irradiation of the titanium target produces an acoustic shockwave, which is transmitted to the optic nerve. The amplitude of the acoustic transients in water was measured using a custom-design calibration chamber containing an ultrasonic immersion transducer (V3194, 100MHz, Olympus, Waltham, MA, USA). After treatment the animals were euthanized and the optic nerve was dissected and prepared for histological analysis to assess laser-induced damage.
Both laser beam delivery systems produced controllable energy dependent acoustic transients in water. The Q-LAS produced no visible damage to the optic nerve during or after the treatment at the gross anatomical level. The free-space system produced visible damage at energies above 50mJ. At energies below visible damage threshold, histological analysis showed superficial damage to the target tissue limited to the dural sheath. No visible damage to the internal structures was observed.
The study demonstrates the feasibility of controlled focal optic nerve injury using laser-induced acoustic transients. This method can serve as an alternate to crush injury models.
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