Dry Eye Disease

Overview

Dry eye disease (DED) is a common, multifactorial disease of the tear film and ocular surface. The Tear Film & Ocular Surface Society (TFOS) defines it as a disease — not merely a syndrome — characterized by loss of homeostasis of the tear film and/or ocular surface, in which tear film instability and hyperosmolarity, ocular surface inflammation and damage, and neurosensory abnormalities act as etiological factors, and which is always symptomatic.¹

Epidemiology & Risk Factors

DED is highly prevalent worldwide, though estimates vary by diagnostic criteria and population studied. Recognized risk factors include older age, female sex, prior refractive or cataract surgery, contact lens wear, chronic use of preserved topical medications, screen use with reduced blink rate, autoimmune disease (e.g., Sjögren syndrome), certain systemic medications (antihistamines, antidepressants, isotretinoin), and environmental factors (low humidity, wind, air conditioning).

Pathophysiology

A self-perpetuating "vicious cycle" underlies DED: tear film instability leads to hyperosmolarity of the tear film, which triggers ocular surface inflammation and epithelial damage; this damage further destabilizes the tear film and can also cause neurosensory changes (initially increased sensitivity, later potentially decreased sensitivity from nerve damage), perpetuating the cycle regardless of the initial trigger.² DED is subclassified into two overlapping mechanistic categories: evaporative (from meibomian gland dysfunction, lid disease, or reduced blink) and aqueous-deficient (from reduced lacrimal gland tear production, as in Sjögren syndrome).¹

Clinical Presentation

Patients report a range of symptoms including ocular dryness, grittiness or foreign-body sensation, burning, fluctuating or blurred vision that improves with blinking, photophobia, and — paradoxically — reflex tearing/epiphora from ocular surface irritation. Symptoms are often worse later in the day, with prolonged reading or screen use, and in dry/windy/air-conditioned environments.

Exam Findings

• Reduced tear meniscus height
• Decreased tear breakup time (TBUT), measured with fluorescein (invasive) or non-invasively with keratography
• Punctate epithelial erosions on fluorescein staining, typically inferior or interpalpebral
• Conjunctival and lid margin lissamine green staining
• Meibomian gland dysfunction signs: gland dropout, plugged orifices, abnormal meibum quality
• Lid margin telangiectasia, anterior/posterior blepharitis

Differential Diagnosis

• Allergic conjunctivitis (itching prominent, papillary reaction)
• Blepharitis/meibomian gland dysfunction (often overlapping and contributory rather than separate)
• Contact lens-related dryness/discomfort
• Neurotrophic keratopathy (decreased corneal sensation, may mimic or coexist with DED)
• Medicamentosa from preserved topical drops
• Ocular surface disease from limbal stem cell deficiency

Management

Diagnosis follows a structured algorithm: symptom screening with a validated questionnaire (the OSDI-6, with a cut-off score ≥4, is the currently recommended tool), followed by objective testing — non-invasive tear breakup time <10 seconds, tear film hyperosmolarity (≥308 mOsm/L in either eye or an interocular difference >8 mOsm/L), or corneal/conjunctival staining meeting defined thresholds — any one of which, combined with a positive symptom screen, confirms the diagnosis.¹ Subclassification into evaporative, aqueous-deficient, or mixed components (assessed via meibography, lipid layer assessment, and Schirmer testing or tear meniscus height) then guides targeted therapy.¹ Non-invasive multimodal diagnostic platforms (e.g., corneal keratography combined with structured reporting tools) can integrate several of these objective signs at once, though such technology remains unevenly available across regions and health systems.³

Management follows a stepped approach based on severity:

1. Education, environmental modification, and preservative-free artificial tears/lubricants
2. Lid hygiene and warm compresses for meibomian gland dysfunction; consideration of oral omega-3 supplementation
3. Topical anti-inflammatory therapy (cyclosporine, lifitegrast) or short-course topical corticosteroids for moderate-severe disease
4. Punctal plugs to reduce tear drainage in aqueous-deficient disease
5. Advanced options for refractory disease: autologous serum tears, scleral contact lenses, in-office meibomian gland treatments (e.g., thermal pulsation), or amniotic membrane for severe surface damage

Complications

• Chronic epithelial breakdown predisposing to infectious keratitis
• Corneal scarring and, rarely, sterile corneal melt/perforation in severe untreated disease
• Reduced quality of life and visual function impacting reading, screen use, and driving
• Contact lens intolerance

Clinical Pearls

• DED is a disease, not a syndrome, and is by definition always symptomatic per the current TFOS consensus¹
• The OSDI-6 with a cut-off ≥4 is the current recommended screening questionnaire, paired with objective testing to confirm diagnosis¹
• Reflex tearing/epiphora can be a presenting symptom of dry eye — don't assume a watery eye rules out DED
• Evaporative DED (often from meibomian gland dysfunction) is more common overall than pure aqueous-deficient disease
• Subclassification (evaporative vs. aqueous-deficient) matters because it changes which treatment (lid hygiene vs. punctal plugs, for example) is most appropriate

Common Pitfalls

• Diagnosing DED on symptoms alone without any objective confirmatory testing
• Treating all dry eye the same way rather than tailoring therapy to evaporative versus aqueous-deficient subtype
• Overlooking meibomian gland dysfunction as a contributor and focusing only on aqueous tear replacement
• Missing an underlying autoimmune cause (e.g., Sjögren syndrome) in severe aqueous-deficient disease
• Assuming reflex tearing means the eye cannot be "dry"