How is the Schirmer test interpreted?

Schirmer Test Interpretation

The Schirmer test is interpreted based on the millimeters of filter paper wetting after a specified time period, with different diagnostic thresholds depending on whether topical anesthesia is used, but it should never be used as the sole criterion for diagnosing dry eye due to its variable results. 1

Test Variants and Their Interpretation

Schirmer I (Without Anesthesia)

• Less than 5.5 mm of wetting after 5 minutes is diagnostic of aqueous tear deficiency 1
• Less than 10 mm of strip wetting in 5 minutes is suggestive of abnormality 1
• Values between 5-10 mm are considered relatively insignificant as a basal secretion score 1

Schirmer II (With Anesthesia/Basic Secretion Test)

• Less than 3 mm after 5 minutes with anesthetic is highly diagnostic of aqueous tear deficient dry eye 1
• Measurements between 3-10 mm can be considered equivocal 1
• Results of 10 mm or less are generally considered abnormal 1
• This variant gives more variable results than testing without anesthesia 1

Schirmer II Reflex Secretion Test

• Wetting of less than 15 mm after 2 minutes (with nasal mucosa stimulation) is considered abnormal 1

Critical Clinical Considerations

Test Reliability and Limitations

• The Schirmer test gives variable results and must not be used as the sole diagnostic criterion for dry eye 1
• An isolated abnormal result can be nonspecific 1
• Serially consistent low results are strongly suggestive of aqueous tear deficiency 1
• The test has poor specificity (51%) compared to other dry eye diagnostic tests 1

Technical Performance Details

• The filter paper strip is placed in the inferior cul-de-sac, usually the temporal one-third of the lid 1
• Test duration is generally 5 minutes 1
• If topical anesthesia is applied, excess fluid should be gently removed from the cul-de-sac prior to insertion of the filter paper 1

Practical Time-Saving Approach

Shortened Test Duration

• A 1-minute Schirmer test with anesthesia correlates highly with the 5-minute test (ICC 0.938 for right eyes, 0.817 for left eyes) 2
• 100% of patients with severe dry eye (5-minute test ≤5.5 mm) had a 1-minute test ≤2 mm 2
• 80% of patients with moderate dry eye (5-minute test 5.5-10 mm) had a 1-minute test between 3-6 mm 2
• A 3-minute test cutoff of 8 mm corresponds to the clinical cutoff of 10 mm for the 5-minute test 3

Common Pitfalls to Avoid

• Do not diagnose dry eye based solely on a single abnormal Schirmer test result 1
• Do not use the Schirmer test with anesthesia if you need more consistent results—the test without anesthesia is less variable 1
• Do not forget to remove excess anesthetic fluid before inserting the filter paper, as this will falsely elevate results 1
• Be aware that multiple factors affect results including male sex, higher age, season, and various topical (prostaglandin, beta-blocker eye drops) and systemic medications (NSAIDs, thyroid hormones, sedatives) 3