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Yan Nan, huika Xia, Xin Hwang, Jie Gao, Mingliang Pu, Laboratory of Vision Restoration; Visual response properties of Y cells after the optic nerve crush in the cat. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):3236. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate visual response properties of Y cells following the optic nerve crush (ONC) in the cat.
The left optic nerve of young adult cats received a mild crush with a 20g power microclip (TKF-2, AROSurgical, Newport Beach, CA). The ONC injury site was 1-2 mm distal to the globe and the crush lasted for 20 second. At 3, 7, and 14 days after ONC, the eyes were removed. The eyecup was prepared as a flat mount in a recording chamber and superfused with oxygenated Ames medium. Extracellular single-unit responses from Y cells in the retinas were recorded.
After optic nerve injury, Y cells showed clear signs of visual functional deterioration. The average Y cell threshold luminance recorded from normal retinas was 1.98 cd/m2, but the threshold went up to 1.14, 1.41, and 1.51 cd/m2 after 3-, 7- and 14-day of ONC, respectively. Similarly, the average contrast threshold recorded from cells in the normal retina was 3.1%, but it elevated to 75%, 42%, and 19% after 3-, 7-, and 14-day of ONC, respectively. Together, optic nerve injury significantly elevated both luminance and contrast thresholds. However, the capability of Y cells to process contrast and luminance information gradually recouped after the 3-day time point. Effects of optic nerve injury at ON- and OFF-channels were also examined. We observed, unlike recordings made from control retinas where most of encountered cells were ON cells (19 ON cells and 6 OFF cells), more OFF cells were recorded (9 OFF-cells and 7 ON-cells) from 3-day retinas.
The optic nerve injury induced rapid visual function deterioration that resulted in degenerated Y-cell visual function, including an elevated luminance threshold and a deteriorated contrast threshold. Furthermore, the ON pathway appears to be more vulnerable to optic nerve injury events. These physiological changes after ONC could be used as objective indicators of early deterioration of visual function in future studies of retinal neurocircuitry remodeling and development of effective treatment strategies for preserving ganglion cell function in optic nerve injury related diseases.
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