The geographical epidemiology of ocular diseases: some principles and methods

With the increasing availability of geographically referenced data in health research the time is ripe to review the use of particular geographical and spatial analysis techniques in ophthalmic research. Analysis of the geographical distribution of ocular diseases, particularly in Britain, has not had a high profile, but there are certain diseases, such as congenital eye malformations in children, where such analysis methods are particularly appropriate. We review the data requirements and then a variety of analytical techniques, some of which partition geographical space into areal units (such as counties or electoral wards), others of which treat space as continuous. We conclude with some comments on software that is available for such analyses.