How much cataract surgery do we have to do? When is enough enough? Around the world, this is a common question asked by governments, regional health authorities, health trusts, hospital managers, operating theatre staff, and ophthalmologists themselves.

These are fair questions. The volume of cataract surgery already has increased dramatically around the world over the past 20 years. It increased approximately fourfold in just 10 years in both the United States and Sweden through the 1980s1 2; and increased threefold in the United Kingdom over this time.3 In many areas cataract surgery now forms over half of all ophthalmic surgery, and in a number of countries cataract surgery has become the most common elective surgical procedure.4 5

There are three factors that influence the amount of cataract surgery that is performed in a community; the age structure of the community, the indications or thresholds that are used for surgery, and the proportion of those who need or are eligible for surgery who actually have surgery. These three factors combine to give the overall “cataract surgery rate” that has been defined by the World Health Organisation as the number of cataract operations performed per million population per year.6

We need to consider the importance and effect of each of these factors.

The single most important “risk factor” for cataract is increasing age. Data from the Visual Impairment Project in Australia are representative of data from other population based studies.7-10 They show that the prevalence of cataract increases dramatically after the fifth decade (40s). By the eighth decade (70s), half will have significant cataract and by the tenth decade (90s) everyone will be affected.11 Similarly, the proportion who have had cataract surgery doubles …