Research overview: the tapetum and overall quantum efficiency of the cat eye

Quantum efficiency describes the fraction of incoming photons that produce a useful visual signal, and the tapetum raises that fraction by recycling light. This overview surveys how the tapetum, together with a wide pupil and dense rods, pushes the cat eye toward high photon utilization in dim conditions. By returning unabsorbed light for a second pass, the reflective layer improves the odds that scarce twilight photons are caught and counted. The survey frames the tapetum as one term in an overall efficiency budget that also includes optical gathering power and neural pooling. Considering quantum efficiency clarifies why cats so outperform humans in faint light despite having coarser acuity. It reframes the tapetum not as a mysterious source of glow but as a measurable contributor to how completely the feline eye exploits the limited light of its hunting hours.