Dry Eyes: Labs, Diagnosis, and Next Steps

Why Your Eyes Feel Dry: The Two Mechanisms

Dry eye disease (DED) is not a single condition. It splits into two pathways: your eyes either produce too few tears (aqueous-deficient) or lose tears too quickly through evaporation. Most patients have a mix of both, but evaporative dry eye driven by meibomian gland dysfunction (MGD) dominates. A multicenter study published in Investigative Ophthalmology & Visual Science found MGD present in 86% of dry eye patients evaluated in clinical settings [1].

Aqueous-deficient dry eye accounts for roughly 10% of cases when isolated. It results from reduced lacrimal gland output. The causes range from aging and medication side effects to autoimmune destruction of the gland, as seen in Sjögren syndrome. Antihistamines, antidepressants (particularly tricyclics and SSRIs), and isotretinoin are among the most common pharmacologic triggers [2].

Evaporative dry eye occurs when the lipid layer of the tear film is inadequate. The meibomian glands, which line the eyelid margins, produce this oily layer. When these glands become obstructed or atrophied, tears spread unevenly and evaporate within seconds. Screen time compounds the problem. Blink rate drops from a normal 15 to 20 blinks per minute to as few as 3 to 4 during concentrated screen use, according to data reviewed in the BMJ [3].

The distinction between these mechanisms matters because it changes what your clinician tests for and what treatment you receive.

How Dry Eye Disease Is Diagnosed in the Clinic

The diagnostic workup begins with standardized symptom questionnaires, but objective testing is what separates treatable subtypes. The Ocular Surface Disease Index (OSDI) is the most widely validated questionnaire, scoring symptoms on a 0-to-100 scale. A score above 33 indicates severe disease [4]. Questionnaires alone miss the cause.

Tear breakup time (TBUT) is the first objective test most clinicians perform. After instilling fluorescein dye, the examiner watches the tear film under a slit lamp. The time from the last blink to the first dry spot is measured. A TBUT below 10 seconds is abnormal. Values under 5 seconds suggest significant evaporative dysfunction [5].

The Schirmer test measures tear production volume. A small filter paper strip is placed inside the lower eyelid. After 5 minutes, wetting of less than 5 mm without anesthesia indicates aqueous tear deficiency. The test is imperfect (sensitivity hovers around 42% for Sjögren-related dry eye), but it remains a standard screening tool recommended by the American Academy of Ophthalmology [6].

Tear osmolarity testing offers a more quantitative assessment. The TearLab system, cleared by the FDA, measures the salt concentration of the tear film. Values above 308 mOsm/L, or an inter-eye difference greater than 8 mOsm/L, support a dry eye diagnosis. The TFOS DEWS II report identified osmolarity as a single best marker for disease severity [7].

Meibography uses infrared imaging to visualize meibomian gland structure directly. Gland dropout or truncation confirms evaporative dry eye and helps guide targeted lid therapy. Not every clinic offers meibography, but it is increasingly available in specialty practices.

Blood Work: When Labs Are Needed and What to Order

Most dry eye cases do not require blood work. Simple MGD or mild aqueous deficiency responds to empiric treatment without a lab draw. Labs become necessary when symptoms are severe, bilateral, accompanied by dry mouth, or resistant to standard therapy. They are also warranted in patients under 50 with unexplained aqueous deficiency.

Sjögren syndrome screening is the primary indication for lab work in dry eye patients. The American College of Rheumatology and European League Against Rheumatism (EULAR) classification criteria require at least one of the following: anti-SSA/Ro antibody positivity, a labial salivary gland biopsy with a focus score of 1 or greater, or an ocular staining score of 5 or higher [8]. In clinical practice, most clinicians start with serology.

The recommended panel includes:

• Anti-SSA (Ro) antibodies: positive in approximately 70% of Sjögren patients. This is the single most sensitive serologic marker [8].
• Anti-SSB (La) antibodies: positive in 40% to 50% of cases, and highly specific when combined with SSA positivity.
• ANA (antinuclear antibody): positive in up to 80% of Sjögren patients, though it is nonspecific. A positive ANA in the setting of dry eyes and dry mouth raises suspicion but does not confirm the diagnosis alone.
• Rheumatoid factor (RF): elevated in roughly 50% of primary Sjögren patients, often prompting evaluation for overlap with rheumatoid arthritis.
• ESR and CRP: general inflammatory markers that help gauge systemic involvement.

Thyroid function tests (TSH, free T4) deserve consideration. Thyroid eye disease, particularly Graves ophthalmopathy, can present with ocular surface irritation that mimics or coexists with dry eye. A 2019 study in Thyroid reported that 22.8% of patients with autoimmune thyroid disease had concurrent dry eye disease [9].

Vitamin A levels are rarely needed in developed countries but should be checked in patients with malabsorptive conditions (celiac disease, inflammatory bowel disease, bariatric surgery history). Vitamin A deficiency causes keratinization of the conjunctival epithelium and represents a reversible cause of severe dry eye [10].

Fasting glucose or HbA1c can be useful. Diabetic patients have a dry eye prevalence roughly double that of age-matched controls, driven by corneal nerve damage and reduced reflex tearing. The Diabetes Care journal has published data showing dry eye prevalence of 54.3% in type 2 diabetes populations [11].

First-Line Treatment: What to Start Before You See a Specialist

Treatment begins at the pharmacy. Preservative-free artificial tears are the foundation of dry eye management, and they work for most patients with mild disease. The TFOS DEWS II management algorithm recommends starting with lubricant drops used 4 to 6 times daily, along with lid hygiene and environmental modification [12].

Artificial tears come in two broad categories: aqueous supplements and lipid-based formulations. For patients with primarily evaporative dry eye (the majority), lipid-containing drops like Systane Balance or Refresh Optive Mega-3 may perform better by reinforcing the deficient oil layer. For aqueous-deficient patients, hyaluronic acid-based drops (such as Hylo) offer longer ocular surface retention than standard carboxymethylcellulose formulations [12].

Warm compresses and lid hygiene target meibomian gland obstruction directly. Applying a warm compress (40 to 45°C) for 10 minutes followed by gentle lid massage helps liquefy stagnant meibum. A randomized trial in Contact Lens and Anterior Eye demonstrated that 4 weeks of consistent warm compress therapy improved TBUT by a mean of 3.1 seconds [13].

Environmental modifications include using a humidifier (target 40% to 60% indoor humidity), positioning screens below eye level to reduce the exposed ocular surface area, and following the 20-20-20 rule: every 20 minutes, look at something 20 feet away for 20 seconds.

Omega-3 fatty acid supplementation was long recommended as an adjunct. The evidence shifted in 2018 when the DREAM trial (Dry Eye Assessment and Management), a multicenter randomized controlled trial of 535 participants funded by the National Eye Institute, found no statistically significant difference between omega-3 supplementation (3,000 mg/day of EPA and DHA) and olive oil placebo at 12 months [14]. The primary outcome (change in OSDI score) improved in both groups, with no between-group difference. Some clinicians still recommend omega-3s for patients with concurrent cardiovascular indications, but the evidence does not support them as a targeted dry eye therapy.

Prescription Therapies for Moderate-to-Severe Dry Eye

When first-line measures fail after 4 to 6 weeks, prescription anti-inflammatory therapy is the next step. Two FDA-approved topical agents target the inflammatory cycle that perpetuates chronic dry eye.

Cyclosporine 0.05% ophthalmic emulsion (Restasis) was the first FDA-approved prescription dry eye drop, gaining approval in 2003. It suppresses T-cell activation on the ocular surface, reducing the inflammatory cascade that damages both the lacrimal gland and conjunctival goblet cells. Clinical trial data submitted to the FDA showed that 15% of cyclosporine-treated patients achieved a 10 mm increase in Schirmer scores at 6 months versus 5% with vehicle [15]. The medication takes 3 to 6 months to reach full effect. Burning on instillation is common initially and often improves over weeks.

Lifitegrast 5% ophthalmic solution (Xiidra), approved in 2016, blocks lymphocyte function-associated antigen-1 (LFA-1), preventing T-cell adhesion and migration to the ocular surface. The OPUS-2 trial (N=718) showed statistically significant improvement in eye dryness score at 12 weeks compared to placebo (treatment difference of -7.85 on a 0-to-100 visual analog scale, P<0.001) [16]. Dysgeusia (an unusual taste sensation) occurs in approximately 16% of patients.

Cyclosporine 0.09% (Cequa), approved in 2018, uses nanomicellar technology to improve corneal penetration compared to the original formulation. In the ESSENCE trial, 17% of patients on Cequa achieved a 10 mm or greater improvement in Schirmer score versus 9% on vehicle at 12 weeks [17].

Varenicline nasal spray 0.03 mg (Tyrvaya), approved in 2021, takes a different approach. It stimulates the trigeminal parasympathetic pathway via nasal mucosa to increase basal tear production. The ONSET-2 trial showed a mean Schirmer score increase of 11.1 mm versus 6.3 mm for placebo at week 4 [18]. The drug avoids direct ocular instillation entirely, which appeals to patients who cannot tolerate eye drops.

Punctal plugs offer a mechanical approach when tear production is borderline. Small silicone or collagen plugs inserted into the tear duct openings (puncta) slow tear drainage, keeping natural and artificial tears on the surface longer. A Cochrane review noted low-quality evidence supporting their use, but clinical experience supports them as an adjunct, particularly in aqueous-deficient disease [19].

When Dry Eyes Signal Something Bigger

Persistent dry eye, especially when paired with other symptoms, can be the first sign of systemic disease. Sjögren syndrome is the classic example. This autoimmune condition targets moisture-producing glands throughout the body, and dry eyes are the presenting complaint in approximately 30% of cases. The mean delay from symptom onset to Sjögren diagnosis is 4.7 years, according to a study in Arthritis Care & Research [20].

Red flags that warrant urgent ophthalmology referral include:

• Vision changes or worsening visual acuity
• Severe eye pain (not just irritation)
• Corneal ulceration or white spots on the cornea
• Unilateral symptoms (asymmetric dry eye can suggest neurological causes)
• Dry eye in patients under 40 without obvious environmental triggers

Rheumatology referral is appropriate when SSA or SSB antibodies are positive, or when dry eyes occur alongside dry mouth, joint pain, fatigue, or parotid gland swelling. Early diagnosis of Sjögren syndrome matters because it carries a 5% to 10% lifetime risk of B-cell lymphoma, making surveillance a priority [20].

Graft-versus-host disease (GVHD) is another serious cause of dry eye that requires prompt recognition. Among patients who have undergone allogeneic stem cell transplantation, chronic ocular GVHD affects 40% to 60%, and it can progress to corneal perforation without aggressive treatment [21].

A Step-by-Step Plan After Reading This Article

Start with the simplest interventions. Use preservative-free artificial tears 4 to 6 times daily for at least 4 weeks. Add warm compresses for 10 minutes once or twice daily. Reduce screen time where possible, or enforce deliberate blinking breaks.

If symptoms persist beyond 4 to 6 weeks, schedule an eye exam specifically for dry eye evaluation. Request TBUT and Schirmer testing. Ask about tear osmolarity if the clinic offers it.

If your clinician identifies moderate-to-severe disease, discuss cyclosporine or lifitegrast. Both require consistent daily use for 6 to 12 weeks before judging efficacy.

If you experience dry mouth alongside dry eyes, ask for SSA/SSB antibodies and ANA. These results take 3 to 7 business days. A positive SSA antibody triggers rheumatology referral for Sjögren syndrome evaluation, including possible labial salivary gland biopsy.

The Sjögren's Foundation patient hotline (1-301-530-4420) provides support and can help locate a rheumatologist with Sjögren expertise in your area. Your starting point for that call should be your lab results in hand.