Epidemiology

Prevalence and Distribution

Dry eye is extremely common, especially in older individuals. It is the most commonly reported reason for seeking ophthalmologic medical care. Various epidemiological studies have found a prevalence range of 5-50%, depending on the geographic region and age of the studied population. In general, the prevalence of signs compared to symptoms of dry eye syndrome (DES), is both higher and more varied. Evidence to date suggests that evaporative dry eye (EDE) is more common than aqueous tear deficient dry eye (ADDE). A Bayesian analysis of 30 prevalence studies published between 1997 and 2021 found a global prevalence for symptomatic disease of 9.12%. Prevalence was higher among women (9.5%) than among men (6.8%). Geographically, Africa showed the highest prevalence (47.9%), followed by Southern Asia (32.0%), Western Asia (29.0%), Eastern Asia (19.4%), Oceania (14.9%), South America (14.7%), Europe (13.7%) and North America (4.6%).

In the United States (US), a retrospective analysis of data from 9.7 million beneficiaries of the Department of Defense Military Health System (DOD MHS) revealed an overall DES prevalence of 5.28%, with a higher prevalence among female MHS beneficiaries (7.78%) compared to male MHS beneficiaries (2.96%). Prevalence was highest (11.66%) for beneficiaries 50 years of age and above. In the period 2008-2012, annual incidence ranged from 0.55% to 0.87%, being higher for female beneficiaries (0.91-1.21%) than male beneficiaries (0.30-0.55%). Like prevalence, annual incidence was highest (1.62%) among persons 50 years of age or older. A systematic review and meta-analysis of prevalence (reported by 10 studies) and incidence (reported by 2 studies) of DES in the US estimated an overall prevalence of 8.1% (range 5.3-14.5%) and a 5-year incidence of 3.5% among adults ≥18 years of age and 7.8% among adults ≥68 years of age.

Although the possible etiologies vary considerably, a number of risk factors have consistently been reported for DES. These include older age, female sex (and, relatedly, estrogen therapy in postmenopausal women or androgen deficiency), use of systemic antihistamines, LASIK and refractive surgery, radiation therapy, vitamin A deficiency, hepatitis C (HCV) infection and haematopoietic stem cell transplantation (HSCT). These and other possible risk factors, organized into categories based on the quality of supporting evidence and whether they can be modified or not, are shown in Table 1-4.

Aerobic exercise may serve as a protective factor, as it has been shown to increase tear secretion. Additionally, light exercise and a low glycemic index diet may help prevent DES and improve symptom severity.

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