Figure 2.
Psychophysical dark adaptation recovery for a normal human subject. The symbols plot measurements of log threshold elevation, following intense exposures that bleached from 0.2% to 98% of the rhodopsin (data from Pugh 22). Horizontal dashed line indicates the cone plateau at 3.6 log units above the absolute scotopic threshold. Grey curves plot the predicted decline of log threshold elevation for a model in which opsin recombines with 11-cis retinal produced by a rate-limited enzymatic reaction (representing, eg, RDH5 or RPE65 activity).25 Exposures ranged from 4.7 to 7.6 log scotopic troland s, and were estimated to have bleached 0.17, 0.5, 1, 3.7, 14, 32, 53, 74, and 98% of the rhodopsin.