Aberrations and Pupil Size:
Patients with complications from refractive surgery often report that their vision seems much better in bright light than dim light. Not only does bright light help compensate for Loss of Contrast Sensitivity, it also shrinks the pupil, reducing the visual aberrations caused by an irregular cornea. The simulation below illustrates the emergence of a significant ghost image as the ambient illumination decreases from normal to dim light conditions. Note how much more compromised vision becomes as contrast decreases, boundaries become indistinct, and a significant ghost image emerges.
See Also: Ghosting Simulator