What Causes Dry Eye

The Seven Major Causes of Dry Eye

Dry eye disease affects hundreds of millions of people worldwide and can significantly impact daily activities like reading, driving, and working at a computer. Research has identified seven primary categories of causative factors that disrupt the delicate balance of the tear film and the ocular surface.

Environmental Conditions

Your surroundings play a significant role in tear film stability. Low humidity environments, such as air-conditioned offices, heated rooms during winter, and airplane cabins, accelerate tear evaporation. Wind exposure, high altitudes, and dry climates further contribute to moisture loss from the ocular surface. Prolonged screen time is another major environmental factor -- studies show that blink rate decreases by up to 60% during concentrated digital device use, leading to incomplete lid closure and increased tear evaporation. Air pollution, including particulate matter and ozone, has also been linked to increased dry eye prevalence in urban populations.

Medications

A wide range of commonly prescribed medications can cause or worsen dry eye as a side effect. Antihistamines, which are designed to reduce allergic responses, also decrease tear production. Antidepressants, particularly tricyclics and SSRIs, can disrupt lacrimal gland function. Beta-blockers used for cardiovascular conditions, diuretics, oral contraceptives, isotretinoin (used for acne), and anticholinergic drugs all have the potential to reduce tear volume or alter tear composition. If you take multiple medications from these categories, the cumulative drying effect can be particularly pronounced.

Surgeries

Ocular surgeries are a well-documented cause of dry eye, sometimes persisting for months or even years post-operatively. LASIK and other corneal refractive procedures sever corneal nerves during flap creation, temporarily disrupting the neural feedback loop that stimulates tear production. Cataract surgery can similarly affect corneal nerves and alter the ocular surface environment. Cosmetic eyelid surgeries (blepharoplasty) may change the lid anatomy, leading to incomplete blink or lagophthalmos, both of which contribute to increased tear evaporation.

Contact Lens Wear

Contact lenses sit directly on the tear film and can disrupt its normal structure and function. The lens divides the tear film into pre-lens and post-lens layers, reducing overall stability. Over time, contact lens wear can decrease corneal sensitivity, leading to reduced reflex tearing. Deposits on the lens surface attract inflammatory mediators, and the mechanical friction between the lens edge and the conjunctiva can cause goblet cell loss, reducing the mucin layer of the tear film. Studies indicate that up to 50% of contact lens wearers experience some degree of dry eye symptoms.

Systemic Disorders

Several autoimmune and systemic conditions are strongly associated with dry eye disease. Sjogren's syndrome, an autoimmune disorder that targets moisture-producing glands, is one of the most severe causes of aqueous-deficient dry eye. Rheumatoid arthritis, lupus, scleroderma, and other connective tissue diseases can affect the lacrimal glands. Thyroid disorders, particularly Graves' disease, can cause lid retraction and increased ocular surface exposure. Diabetes mellitus is associated with decreased corneal sensitivity and reduced tear production, while hormonal changes related to menopause contribute significantly to dry eye in women.

Aging

The natural aging process is one of the most common contributing factors to dry eye. Tear production decreases with age, with some studies reporting a 60% reduction in tear volume by age 65 compared to age 18. The meibomian glands, which produce the essential lipid layer of the tear film, undergo structural atrophy over time. Hormonal shifts, particularly the decline in androgens and estrogen during menopause, further reduce both aqueous and lipid tear components. Age-related changes in lid laxity can also lead to incomplete lid closure during sleep, exacerbating symptoms upon waking.

Trauma

Physical injury to the eye or surrounding structures can cause dry eye through several mechanisms. Direct damage to the lacrimal gland, tear ducts, or corneal nerves disrupts normal tear production and distribution. Chemical burns or thermal injuries to the ocular surface can destroy goblet cells and scar the conjunctiva, severely impairing the mucin layer. Radiation therapy for head and neck cancers can damage the lacrimal glands, leading to chronic aqueous deficiency. Even seemingly minor trauma, such as a corneal abrasion, can temporarily disrupt the tear film and cause acute dry eye symptoms.

Key Risk Factors

While anyone can develop dry eye, certain populations are at higher risk. Understanding these risk factors can help with early identification and prevention:

• Gender: Women are approximately twice as likely as men to develop dry eye, largely due to hormonal influences throughout life, including pregnancy, oral contraceptive use, and menopause.
• Age: Prevalence increases steadily with age, affecting an estimated 30% of adults over 50.
• Geography: People living in arid, windy, or high-altitude environments face greater risk due to increased tear evaporation.
• Occupation: Office workers, pilots, and others who spend long hours in climate-controlled or low-humidity environments are disproportionately affected.
• Screen time: Heavy digital device users are at elevated risk due to reduced blink rates during focused visual tasks.
• Autoimmune history: A personal or family history of autoimmune conditions significantly increases the likelihood of developing dry eye.

If you recognize one or more of these risk factors in your own life, scheduling a comprehensive dry eye evaluation with a qualified eye care provider can help catch the condition early, when it is most responsive to treatment.