Figure 10. Dependence of b-wave recovery time on bleaching strength.

The time required for the amplitude of the b-wave response to reach a criterion level is plotted against bleach magnitude. Results were obtained with test flashes at the higher fixed intensity (0.1 Td s) for all three subjects (filled symbols), and at the lower fixed intensity (0.02 Td s) for subject A.M.C. (○). As a fraction of the dark-adapted sensitivity, the criterion recovery level was set to 25% for the experiments at the lower test flash intensity, and to 40% for the experiment at the higher test flash intensity, corresponding to an equivalent background intensity of ∼0.35 Td (see text, and vertical grey line in Fig. 6). The plotted values were determined from the time intercepts of the fitted I_equiv(t) functions in Figs 8A, 9A and 10 with the criterion level of 25 or 40%. The continuous curve plots the prediction of the MLP rate-limited model of pigment regeneration (from eqn (7); see also Lamb & Pugh, 2004), with standard parameters v = 0.085 min⁻¹ and K_m= 0.2. The plotted curve represents a rotated version of rhodopsin regeneration, starting from the point (B = 1, t = 20.5 min) and proceeding leftwards and downwards; it corresponds to the expected decay of opsin.