Final answer:
Following cataract surgery, the absence of the natural lens, which typically filters out UV light, provides the eye with the ability to detect low-frequency ultraviolet light that it would normally not perceive.
Step-by-step explanation:
People who have the lens of their eye removed because of cataracts are able to see low-frequency ultraviolet because the lens normally blocks low-frequency ultraviolet light. During cataract surgery, the cloudy lens, which is causing the vision impairment, is removed. The natural lens of the eye filters out ultraviolet (UV) light, so its absence following cataract surgery means that more UV light can reach the retina. Therefore, without the lens, the eye becomes more sensitive to low-frequency UV, which leads to the ability to perceive a spectrum of light that is usually invisible to most people.