Extending the recently observed dramatic growth rates of cataract surgery and intraocular lens implantation into the future is not necessarily valid because of changes in population size, new incidence of cataracts, and rates of treatment for patients diagnosed in current as well as in previous years. Accelerated treatment of the pool of previously diagnosed patients caused a sharp growth in cataract surgery since 1980, but at the same time reduced patients and thus the potential for continued high growth rates. This paper describes a model that produces forecasts through explicit consideration of the many aspects of population dynamics. It provides an opportunity to examine how forecasts might vary under different assumptions about advances in medical technology.