Dry eye is a common disorder of the ocular surface that affects millions of people worldwide, with varying severity. At a minimum, dry eye causes discomfort, but it can also cause disabling pain and fluctuating vision, substantially affecting vision-related quality of life by limiting such activities as driving and reading, as well as recreation.1 Dry eye also influences productivity in the workplace by making it more difficult to use a computer or read for extended periods, decreasing tolerance for certain environments, and reducing work time.1 In the United States, the wide prevalence of dry eye imposes a substantial economic burden (an estimated $3.8 billion in health care expenditures annually).2 Each year, the societal costs (i.e., reduced productivity and indirect costs) associated with this chronic condition amount to approximately $55 billion in the United States.2 Dry eye disease is an umbrella term covering a host of symptoms and signs associated with compromised ocular lubrication - that is, reduced quality or quantity of tears on the ocular surface. However, this monolithic approach to dry eye has not served science or patients well. Dry eye has many causes, which often overlap and interact. It frequently occurs with other conditions, is a consequence of environmental triggers, or is caused by medications, including over-the-counter drugs such as antihistamines.The condition can be caused or exacerbated by ocular surgery, computer use, contact-lens use, or low-humidity conditions. Diagnosis, at least initially, often relies on subjective symptoms, with variable presentation and few objective signs that can be assessed in the primary care setting. However, by thinking in terms of the subtypes of dry eye, classified on the basis of risk factors and pathophysiological features, clinicians will be better equipped to diagnose and treat cases. As the population ages, the prevalence of dry eye is likely to increase, yet the condition is often underrecognized and undertreated. This review describes current knowledge of the causes and treatment of dry eye, ongoing research, and future directions for advancing knowledge and treatment of the condition. Copyright © 2018 Massachusetts Medical Society.
