DRY EYE PREVALENCE Dry eye is a disease that affects between 4 and 34% of the population (Lekhanont et al. 2006, Schaumberg et al. 2009). The prevalence increases with age in both females and males (Moss et al. 2008, Schaumberg et al. 2003, Schaumberg et al. 2009) however, women are approximately 2.4 times more likely to develop the disease (Galor et al. 2011). It is estimated that roughly 5 million Americans, 3.23 million women and 1.68 million men over the age of 50 have dry eye (Schaumberg et al. 2003, Schaumberg et al. 2009). However, it has been suggested that an additional tens of millions of people have less severe symptoms of the disease, which only manifest during stressful conditions for the ocular surface, e.g. contact lens wear, airline travel or drafty environmental conditions (Dry Eye Workshop 2007b). The variety of deﬁ nitions and criteria utilized to describe and diagnose the disease, as well as the different experimental designs used to obtain the data are factors likely to explain the large discrepancies in prevalence found
Ocular Surface Center, Department of Ophthalmology, Cullen Eye Institute, Baylor College of Medicine, Houston, Texas; 6565 Fannin Street, NC 205-Houston, TX 77030. aE-mail: [email protected] *Corresponding author
between different studies. For example, some studies used a subjective method (questionnaires) whereas others used objective methods (clinical tests) or a combination of both.