Insufficient amount of tears: aging, decline in lacrimal gland fxn, meds, contact lens use, lacrimal gland obstruction, other
Excessive evaporation of tears: contact lens use, insufficient blink rate, meds, allergic disorders of eye surface, other
Primary or Secondary (e.g. assoc w/SLE, RA) Sjogren's Syndrome

Any process causing chronic eye surface inflammation (allergic, auto-immune, other)
Increased age, women > men
Chronic wind exposure, low humidity, warm temperatures can exacerbate dry eyes from any cause

Chronic discomfort/irritation, sense of dryness, light sensitivity, foreign body sensation
Sometimes blurry vision

Dry Eyes