The number of nuclei spanning the outer nuclear layer at 600–1000 m from the optic nerve in the superior region of the retina in mice of different ages was plotted to determine the kinetics of retinal degeneration. The data were fit with an exponential equation for one-phase decay by non-linear regression to determine the rate constant ( k ), which is reported in Table 1 . Mean values along with the standard deviation were plotted (number of mice, n = 6).