Tear film evaluation: static and dynamic assessments; tear break-up time, Schirmer I. List the indications/contraindications

A. Indications 1. Keratoconjunctivitis sicca 2. Evaluation of ocular discomfort 3. Evaluation of intermittent blurred vision 4. Neurotrophic keratopathy 5. Exposure keratopathy 6. Preoperative evaluation for refractive or cataract surgery

B. Contraindications 1. Inability to cooperate with testing

II. Describe the instrumentation and technique

A. Slit-lamp biomicroscopic examination 1. Measure tear meniscus height

a. Below 0.3 mm is abnormal 2. Observe for presence of debris, mucus in the tear film using slit beam 3. Observe rate of disappearance of dye, such as fluorescein

B. Vital stains 1. Fluorescein

a. Available as .25% solution with an anesthetic, 2% non-preserved unit-dose eyedrop, and impregnated paper strip

b. Moisten a fluorescein strip with a drop of non-preserved saline and touch the inferior palpebral conjunctiva

c. Observe using cobalt blue light d. Measure location and intensity of staining e. Stains areas where epithelial is missing

2. Rose bengal or Lissamine Green a. Available in impregnated strips b. Moisten strip with a drop of non-preserved saline and touch the

inferior palpebral conjunctiva i. Be sure to maximize amount of dye in tear film to avoid

false negatives c. Observe using white light d. Measure location and intensity of staining e. Stains areas of devitalized epithelium (missing mucin layer)

C. Tear break-up time 1. Tear break-up time should be measured prior to the instillation of any

eyedrops 2. Moisten a fluorescein strip with a drop of non-preserved saline and

touch the inferior palpebral conjunctiva 3. Observe using cobalt blue light 4. The patient is asked to blink, then hold the eye open without blinking 5. Time from the last blink until the tear film thins and “breaks up” 6. Take at least three readings

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D. Schirmer 1. Without anesthetic

a. Any tear present is removed from the lower fornix by gentle blotting

b. Whatman #41 filter paper strip (5 mm wide and 35 mm long) is placed across the lower lid at the outer 1/3 of the lid margin

c. The patient is advised not to squeeze the eyelids together d. After 5 minutes the strips are removed and the amount of

wetting measured e. If no tear production at 5 minutes, consider nasal stimulation

2. With anesthetic a. Same as above except a drop of topical anesthetic is first

placed into the eye, and then removed by gentle blotting III. Describe the considerations in interpretation for this diagnostic procedure

A. Vital stains 1. Fluorescein

a. Detects disruptions of intercellular junctions b. If abnormal, consider pattern of staining

i. Diffuse i) Keratoconjunctivitis sicca (severe) ii) Viral conjunctivitis iii) Trauma iv) Toxicity

ii. Inferior staining i) Lagophthalmos ii) Blepharitis iii) Trichiasis iv) Exposure keratopathy

iii. Interpalpebral i) Exposure keratopathy ii) Neurotrophic keratopathy iii) Dry eye syndrome

iv. Superior i) Superior limbic keratoconjunctivitis ii) Foreign body under upper lid iii) Trichiasis

v. 3 and 9 o’clock i) Contact lens

2. Rose Bengal or Lissamine Green a. Stains epithelium devoid of surface glycoproteins (mucin) b. Interpalpebral staining- dry eye syndrome

B. Tear break-up time 1. Normal tear break-up time is over 10 seconds 2. If rapid tear break up time- evaporative type dry eye 3. Consider lipid deficiency or mucin deficiency

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C. Schirmer test 1. Normal values

a. With anesthetic: over 10 mm b. Without anesthetic: over 15 mm

2. Test with anesthesia measures basal level of tear production 3. Test without anesthesia measures reflex and basal level of tear

production 4. Test widely available 5. Test is very operator dependent 6. Poor reproducibility 7. Low value suggests aqueous tear deficiency

Additional Resources

1. AAO, Basic and Clinical Science Course. Section 8: External Disease and Cornea, 2013-2014.

2. AAO, Focal Points: Dry Eye, Module #5, 2006.

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