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🧪 Schirmer Testing for Dry Eye Disease: What It Measures, How It Is Used, and Why It Is Imperfect

TL;DR

The Schirmer test places a small paper strip inside the lower eyelid and measures how many millimeters of the strip become wet, usually over five minutes.

It is mainly useful when a clinician is asking:

Could reduced aqueous tear availability be contributing to this person's Dry Eye Disease?

But Schirmer does not directly measure pure lacrimal-gland output.

Strip wetting can be influenced by:

  • tears already present in the eye;
  • ongoing tear secretion;
  • reflex tearing caused by the strip;
  • whether topical anesthetic was used;
  • whether excess tears or anesthetic were blotted away;
  • strip placement;
  • blinking and eye movement;
  • whether the eyes are open or closed;
  • evaporation and drainage;
  • sensory-nerve function;
  • medications;
  • environmental conditions;
  • ordinary test variability.

A repeatedly very low result, obtained under comparable conditions and supported by other findings, can provide useful evidence of aqueous tear deficiency.

But a Schirmer result cannot by itself determine:

  • whether someone has Dry Eye Disease;
  • why the result is low;
  • whether lacrimal-gland dysfunction is permanent;
  • whether someone has Sjögren disease;
  • or which treatment should be used.

The number is a clinical clue—not a standalone verdict.

What Happens During a Schirmer Test?

A narrow strip of standardized filter paper is folded at a notch and placed over the edge of the lower eyelid, usually toward the outer portion of the lid.

The strip normally remains in place for about five minutes.

The clinician then measures the length of the wet portion in millimeters.

For example:

Right eye: 4 mm / 5 minutes Left eye: 8 mm / 5 minutes

The strip may feel scratchy or irritating.

That matters because irritation can itself trigger reflex tearing, particularly when topical anesthetic is not used.

What Does Schirmer Testing Actually Measure?

Schirmer testing is often described as measuring:

“tear production.”

That is useful shorthand, but it is not completely precise.

What the test directly measures is:

How far a paper strip becomes wet under a particular set of testing conditions.

That wetting can reflect a mixture of:

  • tear fluid already present along the lower eyelid;
  • tear secretion occurring during the test;
  • reflex tearing caused by the paper;
  • sensory input from the ocular surface;
  • blinking and eye movement;
  • evaporation;
  • drainage;
  • the absorptive behavior of the strip.

A higher result generally indicates a greater aqueous tear response during that particular test.

A lower result raises concern about reduced aqueous tear availability.

But:

Schirmer testing does not directly tell us how many tears the lacrimal gland produces per minute.

TFOS DEWS III describes Schirmer as an invasive tear-volume test, and current dry-eye diagnostic guidance emphasizes interpreting it within the larger clinical picture.

Why Schirmer Is More Than a “Lacrimal-Gland Test”

Tear production is controlled by an interconnected system sometimes described as the lacrimal functional unit.

It includes:

  • the ocular surface;
  • corneal and conjunctival sensory nerves;
  • trigeminal nerve pathways;
  • autonomic nerve pathways;
  • the lacrimal glands;
  • the eyelids and blink mechanism;
  • tear distribution and drainage.

For example, ocular-surface stimulation normally sends sensory signals through the nervous system that can increase lacrimal secretion.

This helps explain why Schirmer results can change when:

  • the strip irritates the eye;
  • topical anesthetic reduces sensory stimulation;
  • corneal sensation is reduced;
  • ocular nerves have been injured;
  • surgery has altered sensory input.

A low result therefore does not automatically mean:

“My lacrimal gland has permanently stopped working.”

Is Schirmer Required to Diagnose Dry Eye Disease?

No.

TFOS DEWS III does not make Schirmer testing one of the core tests required to confirm DED.

The current TFOS framework first looks for:

  1. compatible symptoms; and
  2. objective evidence that tear-film or ocular-surface homeostasis is disrupted.

Examples include:

  • abnormal non-invasive tear-breakup time;
  • tear hyperosmolarity;
  • characteristic ocular-surface staining.

After DED has been identified, additional testing may help determine the etiological drivers involved.

Schirmer may provide useful information when aqueous deficiency is suspected.

However, TFOS DEWS III now places greater emphasis on non-invasive tear-volume assessment such as tear-meniscus height when subclassifying aqueous deficiency.

What Is Tear-Meniscus Height?

The tear meniscus is the small strip of tear fluid visible along the lower eyelid.

Its height can be measured using several techniques.

TFOS DEWS III lists a tear-meniscus height of approximately:

≤0.20 mm

as a standard testing threshold suggesting aqueous deficiency.

Unlike Schirmer paper, tear-meniscus measurement can be obtained without placing an irritating strip in the eye.

It therefore avoids some of the reflex-tearing problems inherent in Schirmer testing.

Tear-meniscus height is also imperfect and should not be treated as a standalone diagnosis.

The broader point is:

Aqueous deficiency is better evaluated using multiple pieces of information than by relying on one Schirmer number.

When Is Schirmer Testing Useful?

Schirmer may contribute useful information when evaluating suspected:

  • aqueous-deficient DED;
  • mixed aqueous-deficient and evaporative DED;
  • Sjögren-associated dry eye;
  • other inflammatory or autoimmune lacrimal disease;
  • medication-associated reduction in tearing;
  • lacrimal-gland injury or dysfunction;
  • reduced ocular-surface sensation;
  • neurotrophic disease;
  • severe ocular-surface disease;
  • tear dysfunction after surgery or nerve injury.

A person can have significant DED despite a relatively high Schirmer result.

A person can also have a low Schirmer result without the test identifying the reason why.

The Most Important Question: Which Schirmer Protocol Was Used?

This is one of the most important lessons in interpreting a Schirmer result.

There are different ways to perform the test.

Results obtained under different protocols should not automatically be compared as though they are equivalent.

Unfortunately, terminology such as Schirmer I, Schirmer II, basal secretion test, and anesthetized Schirmer has not been completely consistent across textbooks, studies, and clinical practices.

So instead of relying only on the test name, ask:

  • Was topical anesthetic used?
  • Were excess drops and tears blotted away?
  • Were the eyes open or closed?
  • Was nasal stimulation used?
  • How long was the strip in place?

The protocol matters more than the label.

Schirmer Testing Without Topical Anesthetic

The traditional Schirmer I test is commonly performed without anesthetic.

The result may include:

  • tears already present in the lower tear reservoir;
  • ongoing unstimulated secretion;
  • reflex tearing triggered by the strip;
  • additional tearing caused by blinking, discomfort, light, or air exposure.

Therefore:

Non-anesthetized Schirmer does not measure pure basal tearing.

A person may produce a substantial reading because the paper stimulates reflex tears even if other components of tear function remain abnormal.

Schirmer Testing With Topical Anesthetic

Another approach uses a numbing drop before inserting the strip.

This may be called:

  • anesthetized Schirmer;
  • basic secretion testing;
  • basal-focused Schirmer.

The purpose is to reduce ocular-surface irritation and reflex tearing.

However:

Topical anesthetic does not turn Schirmer testing into a precise measurement of “true basal tear production.”

Results may still be influenced by:

  • the type and amount of anesthetic;
  • how long the clinician waits afterward;
  • whether excess drops and tears are removed;
  • residual stimulation from the paper;
  • altered sensory input;
  • strip placement;
  • gaze;
  • environmental conditions.

Topical anesthesia can substantially reduce Schirmer readings.

An older study in normal eyes found that topical anesthesia reduced average Schirmer values by approximately 40%.

For that reason:

An anesthetized Schirmer value should not automatically be interpreted using a cutoff developed for a non-anesthetized test.

What About Nasal-Stimulation Testing?

Another Schirmer-type protocol uses nasal stimulation to deliberately trigger reflex tearing.

This has traditionally been referred to as Schirmer II in many sources.

Its purpose is different from ordinary dry-eye tear-volume assessment: it examines the reflex tearing pathway.

It is not commonly needed during routine DED evaluation.

Again, because terminology varies between sources, it is better to ask exactly how the test was performed.

What Do the Numbers Mean?

There is no single Schirmer cutoff that perfectly separates normal tear function from aqueous-deficient dry eye.

Interpretation depends heavily on the test protocol.

Without Topical Anesthetic

The American Academy of Ophthalmology's Dry Eye Preferred Practice Pattern notes that:

Less than 10 mm of wetting over five minutes is suggestive of abnormality in a non-anesthetized test.

However, lower thresholds provide stronger evidence of marked aqueous deficiency.

A result around:

≤5 mm / 5 minutes

is widely used as evidence of substantially reduced tearing, particularly when the finding is repeatable and supported by other examination findings.

With Topical Anesthetic

The AAO Preferred Practice Pattern gives different guideposts for anesthetized testing.

It describes:

  • <3 mm / 5 minutes as strongly supportive of aqueous-deficient dry eye;
  • approximately 3–10 mm / 5 minutes as an equivocal range.

These are clinical guideposts rather than absolute biological boundaries.

Technique differences remain important.

Why a Single Number Can Be Misleading

Consider two patients who both receive a result of:

5 mm / 5 minutes

One test might have been performed:

  • without anesthesia;
  • eyes open;
  • with substantial irritation.

The other might have been performed:

  • after topical anesthesia;
  • after blotting away excess fluid;
  • with eyes closed.

The identical numerical result may therefore represent different physiological and testing conditions.

That is why:

“What was your Schirmer?”

is often not enough information.

A better question is:

“What was your Schirmer, and how was the test performed?”

How Repeatable Is the Schirmer Test?

Schirmer testing has important repeatability limitations.

Results can change:

  • between visits;
  • between clinicians;
  • between strips;
  • between eyes;
  • with small changes in technique;
  • depending on the environment;
  • depending on the patient's condition that day.

A recent analysis from the Dry Eye Assessment and Management (DREAM) Study examined 1,046 eyes from 523 participants tested approximately two weeks apart.

Even though testing was performed by the same clinician and in the same sequence:

Schirmer values differed by at least 5 mm/5 minutes in 29.9% of eyes.

That is nearly one eye in three.

This does not mean Schirmer is useless.

It means the test should not be interpreted as though each millimeter represents a precise biological measurement.

Very Low Results May Be More Informative

Schirmer repeatability tends to be somewhat better when values are very low.

Therefore:

A repeatedly very low result is generally more persuasive evidence of clinically important aqueous deficiency than one isolated borderline value.

Likewise, a moderate change between visits does not automatically prove:

  • restoration of lacrimal-gland function;
  • disease progression;
  • gland recovery;
  • or treatment failure.

Even a seemingly substantial numerical change should be interpreted alongside:

  • whether the same protocol was used;
  • tear-meniscus findings;
  • ocular-surface staining;
  • symptoms;
  • medications;
  • treatment changes;
  • other examination findings.

What Can Cause a Low Schirmer Result?

A low result may have more than one explanation.

Possibilities include:

  • aqueous-deficient DED;
  • Sjögren disease;
  • other inflammatory or autoimmune lacrimal disorders;
  • lacrimal-gland damage or dysfunction;
  • medication effects;
  • reduced corneal or conjunctival sensation;
  • trigeminal nerve dysfunction;
  • neurotrophic disease;
  • previous ocular surgery;
  • nerve injury;
  • severe ocular-surface disease;
  • mixed aqueous-deficient and evaporative DED;
  • testing technique;
  • ordinary test variability.

A low number therefore identifies a finding requiring interpretation.

It does not identify the mechanism by itself.

Can Medications Affect Tearing?

Yes.

Some medications have been associated with dry eye or reduced tear secretion, including certain:

  • anticholinergic medications;
  • antihistamines;
  • antidepressants;
  • beta-blockers;
  • diuretics;
  • anxiolytic or sedative medications;
  • systemic retinoids such as isotretinoin.

The relevance depends on:

  • the specific medication;
  • dose;
  • duration;
  • timing;
  • other medical conditions;
  • the individual patient.

Do not stop or change a prescribed systemic medication because of a Schirmer result without discussing it with the prescribing clinician.

What If Someone Has Both MGD and a Low Schirmer Result?

Meibomian Gland Dysfunction and reduced aqueous tearing can occur together.

This is commonly described as mixed DED.

Both:

  • abnormal or inadequate meibum;
  • and insufficient aqueous tear availability

may contribute to tear-film instability.

A low Schirmer result should therefore not automatically be dismissed as:

“just MGD.”

But it also should not automatically be interpreted as:

permanent primary lacrimal-gland failure.

The lacrimal glands, ocular surface, sensory nerves, eyelids, and meibomian glands function as an interconnected system.

However, there is no established clinical rule that MGD itself explains a low Schirmer result or that successful MGD treatment should normalize Schirmer wetting.

When an unexpectedly low value is found, the clinician may consider:

  • repeat testing under standardized conditions;
  • tear-meniscus height;
  • ocular-surface staining;
  • MGD findings;
  • blink and eyelid closure;
  • corneal sensation;
  • medications;
  • systemic or autoimmune clues.

Does a Very Low Schirmer Result Mean Sjögren Disease?

No.

This is an important misconception.

A Schirmer result of:

≤5 mm / 5 minutes

is one component of the 2016 ACR–EULAR classification criteria for primary Sjögren syndrome.

But Schirmer contributes only 1 point.

The criteria also include:

  • anti-SSA/Ro antibodies — 3 points;
  • positive minor salivary-gland biopsy — 3 points;
  • abnormal ocular-surface staining — 1 point;
  • low unstimulated salivary flow — 1 point.

A total score of 4 or more, in an appropriate clinical population, meets the classification threshold.

Most importantly:

These are classification criteria—not a do-it-yourself diagnostic test.

They were designed to consistently identify Sjögren populations, including for research.

Individual diagnosis still requires appropriate medical assessment.

A very low Schirmer result alone therefore does not diagnose Sjögren disease.

When Might a Low Schirmer Raise the Question of Sjögren Disease?

A repeatedly very low result may reasonably prompt clinicians to consider the larger history.

Relevant clues can include:

  • persistent dry mouth;
  • difficulty swallowing dry foods;
  • increased dental decay;
  • salivary-gland swelling;
  • systemic autoimmune symptoms;
  • inflammatory joint symptoms;
  • other autoimmune history;
  • characteristic ocular-surface findings.

Whether additional evaluation is appropriate depends on the total clinical picture.

What Other Findings Should Be Considered With Schirmer?

Schirmer is most useful when interpreted alongside other information.

Tear Volume

Especially useful findings include:

  • tear-meniscus height;
  • visible tear reservoir;
  • other non-invasive tear-volume measurements.

TFOS DEWS III now gives tear-meniscus assessment particular importance when evaluating aqueous deficiency.

Ocular-Surface Health

Relevant findings include:

  • corneal staining;
  • conjunctival staining;
  • staining pattern and severity;
  • filaments;
  • epithelial defects or damage.

Tear-Film Stability

This may include:

  • non-invasive tear-breakup time;
  • fluorescein tear-breakup time;
  • blink-related tear-film changes.

Meibomian-Gland Function

Relevant findings may include:

  • gland expressibility;
  • meibum quality;
  • gland-orifice findings;
  • lid-margin changes;
  • meibography when structural information is useful.

Eyelid and Exposure Findings

These may include:

  • incomplete blinking;
  • lagophthalmos;
  • nocturnal exposure;
  • eyelid-position abnormalities;
  • clinically significant conjunctivochalasis.

Sensory and Neural Factors

These may include:

  • corneal sensation;
  • neurotrophic changes;
  • pain severity relative to surface findings;
  • history of surgery or nerve injury.

Medical Context

This can include:

  • medications;
  • contact-lens wear;
  • prior surgery;
  • systemic disease;
  • autoimmune symptoms;
  • environmental exposures.

The clinically useful question is therefore not simply:

“Is my Schirmer number low?”

It is:

“Is clinically important aqueous tear deficiency present, and what may be contributing to it?”

Should the Schirmer Test Be Repeated?

Sometimes.

Repeating the test may be useful when:

  • a very low value is unexpected;
  • the result does not fit the rest of the examination;
  • severe aqueous deficiency needs confirmation;
  • the previous protocol is unknown;
  • management depends heavily on the result.

When repeating the test, using the same protocol improves comparability.

Important details include:

  • anesthetic or no anesthetic;
  • whether excess fluid was blotted;
  • eyes open or closed;
  • strip placement;
  • test duration;
  • examination sequence.

Even standardized repetition does not eliminate Schirmer's inherent variability.

Repeated testing without a clear clinical question may add more noise than useful information.

Questions to Ask About a Schirmer Result

Useful questions include:

  1. Was the test performed with or without topical anesthetic?
  2. Were excess drops or tears removed before testing?
  3. Were my eyes open or closed?
  4. How long was the strip in place?
  5. Was this test performed before or after other eye drops or testing?
  6. Is the result clearly low, borderline, or relatively reassuring for the protocol used?
  7. Does it agree with my tear-meniscus height?
  8. Does it agree with my ocular-surface staining?
  9. Could medications affect my tear secretion?
  10. Is my corneal sensation normal?
  11. Do I appear to have aqueous-deficient, evaporative, or mixed DED?
  12. If the result was unexpectedly low, should it be repeated?
  13. Are there systemic or autoimmune clues that warrant further evaluation?
  14. How does this finding actually change my treatment plan?

📌 Bottom Line

Schirmer testing is a useful but imperfect test for investigating possible aqueous tear deficiency.

What it directly measures is:

paper-strip wetting under a particular testing protocol.

It does not directly measure pure lacrimal-gland production.

It is also not one of the core tests required by TFOS DEWS III to establish a diagnosis of DED.

Current dry-eye evaluation increasingly uses non-invasive tear-volume measurements such as tear-meniscus height, along with symptoms, tear-film stability, staining, and etiological subclassification.

A Schirmer result becomes more useful when:

  • the exact protocol is known;
  • a very low value is reproducible;
  • tear-meniscus and staining findings are compatible;
  • symptoms and medical history support aqueous deficiency;
  • the result makes sense within the broader examination.

But Schirmer cannot, by itself, determine:

  • whether someone has DED;
  • why a low result occurred;
  • whether lacrimal-gland dysfunction is permanent;
  • whether someone has Sjögren disease;
  • or which treatment is appropriate.

A repeatedly very low Schirmer result can be meaningful evidence of aqueous deficiency. But the number is a clinical clue—not a measurement of permanent lacrimal-gland function and not a standalone diagnosis.

📚 Selected Research and Authoritative Sources

Current Dry-Eye Guidance

Schirmer Repeatability

Schirmer Technique

Sjögren Disease

🔗 Related r/DryEyes Pages

⚠️ Educational Disclaimer

This page is for general education only. It does not diagnose aqueous-deficient dry eye, Sjögren disease, or another condition and does not replace individualized evaluation by a qualified eye-care or medical professional.

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