The Schirmer test is a simple office procedure that measures how much moisture your eyes produce over a set time, primarily used to help diagnose dry eye disease. A small strip of filter paper is hooked over the lower eyelid, left in place for five minutes, and the length of wetted paper is read in millimeters. Despite being over a century old and easy to perform, the test has well-documented limitations in reproducibility and sensitivity, which is why clinicians rarely rely on it alone.
What the Test Is Actually Measuring
Your eyes constantly produce tears through a layered system. The watery (aqueous) layer, secreted mainly by the lacrimal gland above each eye, makes up the bulk of your tear film. The Schirmer test targets this aqueous component. When the strip touches the inside of your lower lid, it wicks up whatever moisture is present, and the millimeter reading gives a rough estimate of tear volume produced during those five minutes.
This matters because dry eye disease falls into two broad categories. One is aqueous-deficient dry eye, where the lacrimal gland simply does not produce enough of the watery layer. The other is evaporative dry eye, where tears are produced in adequate volume but evaporate too quickly, usually because the oily outer layer is compromised. The Schirmer test is better suited to catching the first type. When a clinician sees low Schirmer results alongside other findings, that pattern can point toward aqueous deficiency and trigger further workup, including screening for conditions like Sjögren’s syndrome.
How the Test Is Performed
The procedure itself is straightforward. You sit in an exam chair, and the clinician folds the rounded end of a standardized filter-paper strip over the margin of your lower eyelid, typically near the outer corner. You close your eyes gently or look straight ahead, and the strip stays in place for five minutes. When time is up, the strip is removed and the clinician reads how many millimeters of paper got wet from the folded notch onward.
There are two main versions. In Schirmer I without anesthesia, the strip goes in with no numbing drops, so the reading reflects both your baseline tear production and any reflex tearing triggered by the strip’s irritation. In Schirmer I with anesthesia, numbing drops are instilled first, then the eye is gently blotted dry before the strip is placed. The idea is to suppress reflex tearing and isolate the baseline, or “basal,” secretion rate. In practice, the anesthetized version produces lower readings because reflex tearing is dampened, though studies have shown that anesthesia cannot completely eliminate the reflex component.
A third variation, Schirmer II, involves deliberately stimulating reflex tearing by irritating the nasal mucosa with a cotton swab after anesthesia. This version is less commonly used in routine practice and is mostly reserved for evaluating whether the reflex arc itself is intact.
What the Numbers Mean
The most widely used cutoff is 10 millimeters of wetting in five minutes for the test without anesthesia. Readings below that are generally considered suggestive of reduced tear production. A stricter cutoff of 5 millimeters is sometimes used to flag more severe deficiency. For the anesthetized version, the expected normal range is lower, and readings under 5 millimeters are typically considered abnormal.
These thresholds carry a real trade-off between catching true cases and avoiding false alarms. A Japanese study evaluating the Schirmer I test found that using the 5-millimeter cutoff gave about 80% sensitivity and 53% specificity, while the 10-millimeter cutoff pushed sensitivity up to roughly 88% but dropped specificity to just 35%.1PubMed. Diagnostic usefulness and cutoff value of Schirmer’s I test in the Japanese diagnostic criteria of dry eye In plain terms, the more generous cutoff catches more people who truly have dry eye but also flags a lot of people who do not. The stricter cutoff misses fewer healthy people but lets more genuine dry eye cases slip through.
This is why the Schirmer test works best as one piece of a larger puzzle rather than a standalone verdict. When combined with a symptom questionnaire and a tear break-up time measurement, the diagnostic picture improves dramatically. One study comparing multiple test combinations found that pairing a symptom index, tear break-up time, and the Schirmer test together achieved sensitivity near 100% and specificity around 95%.2PLOS ONE. Comparison of Diagnostic Tests in Distinct Well-Defined Conditions Related to Dry Eye Disease
Why Results Can Be Inconsistent
One of the most common frustrations with the Schirmer test is that the same person can get meaningfully different readings on different days, or even between eyes tested minutes apart. Several factors contribute to this variability, and understanding them helps explain why your doctor may not put all their diagnostic eggs in this one basket.
The reflex tearing problem is the most fundamental. Even a tiny tickle from the strip can provoke extra tear flow, and the degree of that reflex varies from person to person and visit to visit. Applying anesthetic drops before the test reduces but does not eliminate this effect.3JAMA Ophthalmology. Schirmer’s Test: A Closer Look A person who is anxious, who recently rubbed their eyes, or who has mild allergies that day might produce more reflex tears than on a calm morning.
Room humidity is another variable. In laboratory testing, Schirmer strips showed clearly shorter wetting lengths when the surrounding air was drier, because moisture evaporates from the exposed paper faster in low-humidity environments.4Cornea. Effects of Humidity on Tests of Tear Production In that same study, people with severe dry eye were less affected by humidity changes than people with normal tear production, likely because there was so little moisture on the strip to begin with. Interestingly, a large multicenter trial looking at real-world environmental data found no clear association between Schirmer results and outdoor environmental conditions, suggesting that the controlled indoor climate of most exam rooms may buffer against this effect in practice.5PubMed Central. Climatic and Environmental Correlates of Dry Eye Disease Severity: A Report From the Dry Eye Assessment and Management (DREAM) Study
Even the brand of filter paper strip matters. A study comparing five commercially available Schirmer strips found they differed in width, weight, scale markings, and how far tears migrated along them for the same applied volume. The measurement error attributable to brand differences alone was roughly 3 millimeters.6PubMed Central. Evaluating Moisture Migration in Schirmer Test Strips: Exploring Brand-Specific Variations and Introducing Calibration and Conversion Methods When the diagnostic cutoff is 5 or 10 millimeters, a 3-millimeter swing from the strip alone can flip a result from normal to abnormal.
Medications and Surgery That Shift Results
If you are taking certain medications, your Schirmer results may be lower than your underlying tear production warrants. A study examining the relationship between common medications and Schirmer scores found that several drug classes were associated with reduced readings, including prostaglandin and beta-blocker eye drops (used for glaucoma), oral anti-inflammatory drugs, acid-reflux medications, thyroid hormones, combined estrogen-progesterone drugs, and sedatives.7PubMed. Schirmer test results: are they associated with topical or systemic medication? If you are on any of these and your eye doctor orders a Schirmer test, mentioning them beforehand can help with interpretation.
Refractive surgery is another well-known disruptor. LASIK involves cutting a flap in the cornea, which severs some of the nerves responsible for the reflex tearing loop. A study tracking patients after LASIK for nearsightedness found that the average Schirmer value dropped from about 8 millimeters before surgery to roughly 4.5 millimeters one month afterward. By 12 months, the average had recovered to around 8 millimeters, but many patients experienced significant dry eye symptoms in the interim.8Clinical Ophthalmology. Incidence and management of symptomatic dry eye related to LASIK for myopia, with topical cyclosporine A This temporary dip is why eye surgeons routinely check tear production before LASIK and counsel patients about the likelihood of post-surgical dryness.
When It Points Toward Something Bigger
For most people, a low Schirmer result simply confirms the dry eye their symptoms already suggest, and treatment involves lubricating drops or lifestyle adjustments. But persistently low values, especially when combined with dry mouth, can raise a flag for Sjögren’s syndrome, an autoimmune condition in which the immune system attacks moisture-producing glands throughout the body.
The Schirmer test is one of the objective criteria used in classifying Sjögren’s syndrome, and when aqueous-deficient dry eye is identified, further investigation to distinguish between Sjögren’s-related and non-Sjögren’s causes is recommended.9PubMed Central. Making the diagnosis of Sjögren’s syndrome in patients with dry eye That said, the Schirmer test alone is a modest predictor of Sjögren’s. In a study of over 500 patients with dryness symptoms, the Schirmer test’s discriminative ability for Sjögren’s was relatively low compared with blood tests for specific antibodies or salivary gland biopsy.10PubMed. Application of classification criteria of Sjogren syndrome in patients with sicca symptoms: Real-world experience at a medical center The test helps narrow the field, but confirming Sjögren’s typically requires blood work and sometimes a lip biopsy.
Tear Production in Newborns and Infants
If you have ever noticed that very young babies sometimes cry without visible tears, that observation is backed by measurable data. Premature infants have dramatically lower Schirmer scores than full-term newborns. One study found average Schirmer values of only about 1.5 millimeters in premature babies compared with around 15 millimeters in term babies.11PubMed. Tear function and ocular surface findings in premature and term babies The lacrimal gland simply has not matured enough to produce a full tear film in the earliest weeks of life, and tear production ramps up over the first few months. This is normal physiology, not a sign of dry eye disease, and clinicians interpreting Schirmer results in infants use very different expectations than for adults.
Alternatives and Complementary Tests
Given the Schirmer test’s variability, clinicians often use additional tools either alongside it or as substitutes when circumstances call for something faster or more comfortable.
The phenol red thread test works on a similar principle but uses a thin cotton thread impregnated with a pH-sensitive dye instead of a filter-paper strip. The thread is placed over the lower lid for just 15 seconds, and the dye changes color where tears wet it. Proponents argue it is faster, more comfortable, and causes less reflex tearing.12PubMed Central. Evaluation of Phenol Red Thread test versus Schirmer test in dry eyes: A comparative study However, head-to-head comparisons have found weak agreement between the two tests, meaning they do not consistently classify the same patients as dry or normal.13PubMed. Phenol red thread test vs Schirmer’s test: a comparative study Whether that reflects the phenol red thread measuring something slightly different (the existing tear meniscus rather than production rate over time) or simply the noise inherent in both tests remains debated.
Tear osmolarity measurement takes a different approach entirely. Instead of measuring volume, it measures how concentrated the salt content of your tears is. Higher osmolarity signals an unhealthy tear film. Osmolarity correlates strongly with tear break-up time but shows a weaker or absent direct correlation with Schirmer scores in some studies.14Korean Journal of Ophthalmology. Correlation between Tear Osmolarity and Other Ocular Surface Parameters in Primary Sjögren’s Syndrome In Sjögren’s patients specifically, one study did find a meaningful negative correlation between osmolarity and Schirmer values, suggesting the two tests converge when aqueous deficiency is severe enough. In milder or non-Sjögren’s dry eye, the relationship is less consistent.15Taylor & Francis Online. Correlation of Non-invasive Tear Break-Up Time with Tear Osmolarity and Other Invasive Tear Function Tests
Tear meniscus height measurement, done with specialized imaging or even a self-administered strip, offers another angle. Research has shown that tear volume fluctuates throughout the day, peaking upon waking and declining through the evening.16PLOS ONE. Diurnal variation of human tear meniscus volume measured with tear strip meniscometry self-examination This daily rhythm is worth knowing because it means a Schirmer test performed first thing in the morning and one performed in the late afternoon might give different impressions of the same person’s tear status.
The Test in Veterinary Medicine
The Schirmer test is not just a human diagnostic tool. Veterinarians use an identical-looking strip to screen dogs for keratoconjunctivitis sicca, commonly called dry eye, which is especially common in breeds like Cocker Spaniels, Bulldogs, and West Highland White Terriers. Normal values in dogs run higher than in humans. Studies report average Schirmer I readings around 20 millimeters per minute in healthy dogs, and values below about 15 are considered borderline while readings under 10 suggest clinically significant dry eye.17PubMed. Tear film breakup time and Schirmer tear test in normal dogs: Effects of age, sex, reproductive status, skull type, and nasolacrimal duct patency
Placement of the strip matters for dogs, too. A study comparing dorsal and ventral placement in the conjunctival pocket found that ventral placement yielded higher readings, with an average difference of about 3 millimeters.18PubMed Central. Schirmer tear test I in dogs: results comparing placement in the ventral vs. dorsal conjunctival fornix And just as with people, environmental humidity can nudge canine Schirmer results up or down, though in average indoor conditions the effect is unlikely to change a clinical interpretation.19PubMed. Environmental relative humidity affects Schirmer tear test results in normal dogs
Canine dry eye, unlike most human dry eye, is often immune-mediated and progressive, so catching it early with routine Schirmer screening in at-risk breeds can prevent corneal damage. Treatment usually involves immunosuppressive eye drops like cyclosporine or tacrolimus, and veterinarians use serial Schirmer tests to track whether the medication is restoring adequate tear production over time.
Getting the Most Out of a Schirmer Test
If your eye doctor orders a Schirmer test, a few practical things can help ensure the result is as meaningful as possible. Mention any medications you are taking, since several common drug classes can lower tear output independently of any eye disease. If you wear contact lenses, your clinician will likely ask you to remove them before testing, as lenses alter the tear film. Try not to rub your eyes or use eye drops in the hour before the test, since both can temporarily change tear dynamics.
Keep in mind that a single Schirmer reading is a snapshot, not a verdict. If you score borderline on one visit, your doctor may repeat the test on another day, combine it with other measurements, or simply treat based on your symptoms rather than a number. Dry eye is ultimately a clinical diagnosis informed by how your eyes feel, how the surface looks under a slit lamp, and what the various tests suggest when taken together. The Schirmer strip is one voice in that conversation, useful but far from the last word.