Which equation describes the process of dark adaptation?

The process of dark adaptation is primarily described by the Dowling-Rushton equation. This equation characterizes the changes in visual sensitivity that occur when individuals transition from a well-lit environment to one with low light levels. During dark adaptation, the visual system gradually becomes more sensitive due to processes that occur within the photoreceptors, particularly the regeneration of rhodopsin in rods, which are responsible for vision in low light conditions.

The Dowling-Rushton equation models how the sensitivity of the visual system increases over time as it adjusts to darkness. This adaptation process explains why, in dim conditions, objects become more discernible as time passes, despite initially being hard to see. The equation captures the dynamics of visual sensitivity as a function of time, reflecting the physiological changes occurring in the retina.

In contrast, the Weber-Fechner law relates to the perception of changes in stimulus intensity and is not specifically focused on the adaptation to dark. Fick's law deals with diffusion processes and is not relevant to visual adaptation, while Stevens' power law explains the relationship between stimulus magnitude and perception, but it also does not capture the specific adjustments made by the visual system during dark adaptation.