The age specific prevalence and incidence of cataract are combined demographic data to provide an estimate of the cataract pool within the UK population. Cataract surgery rates and age specific mortality rates are then combined with the pool data in a holistic ‘system dynamics’ model to explore how the cataract pool might change over a 5 year period, given a series of options in the levels and pattern of cataract surgery. Finally, the cost to the NHS of the various options are considered.