Schirmer Test

The Schirmer test measures how much tear fluid the eye produces. A thin strip of filter paper is placed in the lower eyelid, and the length of paper that is wet after 5 minutes shows the amount of tears. It is a simple, cheap, bedside test of aqueous tear production, used in the diagnosis of dry eye and Sjogren syndrome.

The strip is 5 mm wide and 35 mm long, with a notch at one end. The notch is folded and placed over the lower lid margin at the junction of the middle and outer third, and the patient sits with the eyes gently closed or looking forward. The test takes 5 minutes. There are two versions.

The Schirmer 1 test, without anaesthesia, measures the total tear secretion (the basic and the reflex part together). The Schirmer 2 test, done after topical anaesthesia, measures basic secretion only, because anaesthesia removes the reflex from the surface of the eye. A third version uses the nose to stimulate reflex tearing, which tests the reflex arc and the lacrimal gland reserve.

In young healthy adults, more than 15 mm is wet after 5 minutes. A reading under 10 mm suggests aqueous deficiency, and under 5 mm is severe. Dry eye affects about 5 to 35% of adults, depending on the definition and the population, and rises with age. Sjogren syndrome affects about 0.5 to 1% of the population, mostly women over 40 years, and a low Schirmer test is one of the criteria for diagnosis.

Indications.

• Symptoms of dry eye: burning, grittiness, redness, foreign body sensation, light sensitivity, fluctuating vision, and stringy discharge.
• Suspected Sjogren syndrome, in patients with dry eyes and dry mouth, joint pain, parotid swelling, or abnormal antibodies.
• Systemic diseases with dry eye: rheumatoid arthritis, lupus, scleroderma, sarcoidosis, graft-versus-host disease, thyroid eye disease, and vitamin A deficiency.
• Persistent corneal epithelial defects, keratitis, and recurrent corneal erosions.
• Before laser refractive surgery or cataract surgery, and with contact lens intolerance.
• Facial nerve palsy, with an assessment of lacrimal gland function, and to decide eye protection.
• Medicine related dry eye (antihistamines, antidepressants, antimuscarinic drugs, diuretics, isotretinoin, and others), and to follow treatment.
• Infants and children with suspected alacrima (Allgrove syndrome, familial dysautonomia).

Not indicated alone for diagnosing the cause of dry eye, since other tests are needed, and not used for watery eyes from blocked tear ducts, for which irrigation and imaging are used.

Contraindications and precautions.

• No contraindications. The test is safe.
• Open globe injury or recent eye surgery: the test is delayed, to avoid pressure and contamination.
• Active infection of the conjunctiva or lids: sterile strips are used and discarded, with hand washing.
• Contact lenses are removed before the test, and the patient is asked to avoid eye drops for at least 30 minutes to 2 hours beforehand, since drops change the result.
• Topical anaesthesia (Schirmer 2) is not used in a patient with allergy to the drug.
• The patient is asked not to rub, squeeze, or blink forcefully during the test, and the room is kept at a stable temperature, without wind or a fan.
• Other eye tests, such as fluorescein staining and tonometry, are done after the Schirmer test, since they alter the tear film.

Preparation and technique.

The patient is seated in a quiet room with a normal temperature and humidity, and is asked to look up. The lower lid is gently pulled down, and the folded end of the strip is hooked over the lid margin at the lateral third, without touching the cornea. The patient closes the eyes gently or looks forward, and is asked to blink normally.

For Schirmer 2, a drop of local anaesthetic is placed in the lower fornix, excess fluid is wiped away, and the test starts after about 1 to 2 minutes. The strips are left in place for 5 minutes, the patient is then asked to open the eyes, the strips are removed, and the length of the wet area measured immediately from the notch with the scale on the strip. Both eyes are tested together.

Normal appearances.

In the Schirmer 1 test, normal wetting is more than 15 mm in 5 minutes. A value of 10 to 15 mm is borderline in some references, and values decrease with age, so older people often have 10 to 15 mm. In the Schirmer 2 test, normal basic secretion is about 10 mm or more in 5 minutes. A difference of less than 5 mm between the two eyes is normal.

Interpretation.

• Under 10 mm in 5 minutes (without anaesthesia): reduced tear production (aqueous deficient dry eye). A value of 5 to 10 mm is mild to moderate, and under 5 mm is severe.
• Under 5 mm in the Schirmer 2 test: reduced basic secretion, which is typical of Sjogren syndrome and lacrimal gland failure.
• Low Schirmer 1 but normal Schirmer 2: reduced reflex tearing, or an effect of the anaesthetic drop or the eye surface.
• Normal Schirmer test with symptoms: evaporative dry eye from meibomian gland dysfunction and blepharitis, ocular surface disease, or allergy and neuropathic pain, and other tests such as tear break up time are needed.
• Very high wetting (over 30 mm) with symptoms: reflex tearing from irritation, or tear drainage problems.
• Absent tearing: alacrimia, facial nerve lesions proximal to the geniculate ganglion, or autonomic disease.
• The result is combined with symptoms, tear break up time, ocular surface staining, and systemic tests, and is not used alone for diagnosis.
• In Sjogren syndrome, a value of 5 mm or less in 5 minutes in at least one eye is one of the diagnostic criteria, together with antibodies, ocular staining, salivary gland findings, and biopsy.

Critical values and findings needing immediate action.

• There are no emergency values.
• Very low tear production with a corneal ulcer, melting, or perforation: urgent referral to an ophthalmologist.
• Very low tear production with new systemic symptoms (dry mouth, joint pain, rash, parotid swelling, neuropathy): prompt workup for Sjogren syndrome and other autoimmune disease.
• Dry eye after a facial nerve palsy, coma, or in an intensive care patient: urgent eye protection, lubricant and taping of the lids, to prevent exposure keratitis.
• A new severe dry eye in a patient on a new drug or after stem cell transplantation: urgent review for graft-versus-host disease or drug cause.

Limitations and artefacts.

• The test has poor repeatability, with large variation from day to day and between the eyes, and a single test is of limited value. The test is repeated when the result is borderline.
• Reflex tearing from irritation by the strip itself can give falsely high values, and the patient's anxiety and eye movements affect results.
• Anaesthetic use, room humidity, wind, air conditioning, time of day, and previous drops change results.
• Sensitivity and specificity for dry eye are moderate (about 60 to 80%), and a normal test does not exclude disease, and low values are found in healthy older people without symptoms.
• Different strip types and methods (with or without anaesthesia, eyes open or closed) give different values.
• Misplaced strips that touch the cornea irritate the eye and cause tearing.
• The test measures only the aqueous part of the tear, and does not measure the oil layer, tear quality, or stability.
• Results in infants and young children are unreliable because of crying.

Special groups.

• Older adults: lower tear production with age, and a high rate of dry eye, particularly in postmenopausal women.
• Patients with suspected Sjogren syndrome: the test is repeated, with ocular surface staining, antibodies against Ro and La antigens, salivary flow measures, and when needed salivary gland imaging or biopsy.
• Contact lens wearers: intolerance may be an early sign of dry eye.
• Patients after refractive surgery: tear production falls for months, and symptoms may be severe.
• Patients on drugs that dry the eye: review of the drug list.
• Patients with facial palsy or exposure keratopathy: the test informs the need for protection and lubrication.
• Regions: the test is inexpensive and can be done anywhere, and is useful for screening. Dry eye is common in hot, dry and dusty climates, and in places with high smoke exposure. Vitamin A deficiency causes severe dry eye and corneal damage (xerophthalmia) in children, and trachoma damages the tear producing glands, and both are important causes of corneal blindness.

Follow up tests.

• Tear break up time, ocular surface staining with fluorescein and lissamine green, and tear film osmolarity.
• Examination of the lid margins and meibomian glands.
• Blood tests: antinuclear antibodies, rheumatoid factor, antibodies against Ro and La, immunoglobulins, and thyroid tests, for autoimmune disease.
• Salivary flow tests and, when indicated, minor salivary gland biopsy.
• Serum vitamin A level, where deficiency is suspected.
• Chest imaging and angiotensin converting enzyme for sarcoidosis, where suspected.
• Review of the eye surface and treatment at regular intervals.