Glaucoma is a chronic progredient neuropathy with typical structural changes at the optic nerve head and functional defects in the visual fields leading to blindness at the end stage. It is estimated that 60.5 million people worldwide will have this disease by 2010 and this number will increase to about 80 million by 2020. Glaucoma is the second leading cause of blindness in the world.1 Furthermore, dry eye disease (DED) is a leading cause of patient visits to ophthalmologists.2 Both glaucoma and DED are multifactorial disorders.3,4 In a review of the prevalence of DED it was shown that the variation of prevalence of DED across studies is very high, differing from <0.1 to 33%,5 depending on how DED was defined. However, in large studies the age-adjusted prevalences at >50 years of age in the US and Spain were from 3.9 to 11.9%,6–8 and at ≥65 years between 15 to 34%.9 At this age, the prevalence of DED increased with age and with female gender. Since glaucoma and DED are very common in the elderly, we were interested in the prevalence of DED in different glaucoma types and in a very large sample size. The German Glaucoma and Dry Eye Register includes analysable data from a total of 20,506 individuals with diagnosed glaucoma taken from 900 ophthalmological centres across Germany. This information has allowed the relationship between the occurrence of dry eye and potential causative factors to be dissected in detail.10 Overall, 52.6% of glaucoma patients have a concomitant diagnosis of dry eye versus 47.4% who do not. Incidence of Concomitant Diseases Patients were asked directly about any concomitant illnesses and vascular risk factors they were aware of being affected by, and 16 such health concerns are found to co-exist with glaucoma. Irrespective of glaucoma type, hypertension is the most frequent of these, being reported by 48.1% of patients, followed by diabetes (22.5%), dry mouth, nose and skin (11.3%) and obesity (11.2%). Overall, the presence of any concomitant disease increases the percentage of dry eye reported by glaucoma patients. Of those glaucoma patients with dry mouth, noseand skin, 75.5% also suffer from dry eye, and it is found in 68.2% of those with depressive episodes, 66.1% of those with arthritis and 65.6% of those with skin diseases.