The epidemiological research potential of such a resource is obvious A recent survey of ophthalmologists in the United Kingdom showed that 30% have access to electronic patient records (EPR), and about two thirds of these used the EPR for almost all of their cataract surgery.1 That shows great progress over the past few years—one wonders if they appreciate quite what they are achieving. They are building the most powerful database of cataract surgery the world has ever seen. Will it one day turn on them and devour them?—great good can come from the use of data, but also great evil. We stand at a crossroad right now and which road we take will shape our individual and collective destinies, our relationship with patients, and our standing in society. While patient records continue to be written on paper, individual surgeon performance is available in theory but in practice it is hidden. The sheer number of patient notes on those long shelves in the hospital basement is as good an impediment to casual scrutiny as any lock and key. Layer upon layer of obstacles lie in wait for any who dare audit the data—identifying the relevant records, locating them, deciphering them, abstracting necessary gems and collating these. At each obstacle a little integrity is lost such that the output is a subset of a subset of a temporal cross section of what …