Blue light-filtering intraocular lenses (IOLs) have become part of the modern cataract surgeon's armamentarium and are widely used. Their advocates suggest they may protect against light-induced retinal damage and also affect the development or progression of age-related macular degeneration. Much of the evidence for photoprotection is theoretical or based on observations in cell culture or animal experiments, with little clinical information to date. Although arguments remain theoretical, there is now emerging clinical data on the use of these IOLs in patients looking at the benefits and potential side effects. In this review, we consider the background to the development of these IOLs, the evidence for a reduction in short-wavelength light exposure protecting retinal cells and function, and the possible disadvantages of IOLs resulting from their reduced light transmission. We place this information in context with regard to patients having cataract surgery and the day-to-day conditions in which they live.