Table 1.
Observation or Test | What is Examined | Tools | Sign of Dry Eye |
---|---|---|---|
1. Direct Observation | Tear function, tear stability and ocular surface | Corneal light reflex biomicroscope (additional instruments are available in the research setting) | Tear film instability Ocular surface irregularity |
Meibomian gland disease | Biomicroscope | Presence of foamy debris | |
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2. Osmolarity | Tear composition: levels of inflammatory mediators in tear film and conjunctiva | Osmometer (mostly limited to research settings but units are increasingly available for clinical practice) | Elevated osmolarity of the tear film |
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3. Fluorescein Tear Break-Up Time | Tear film stability | Fluorescein dye Slit-lamp |
Rapid tear film breakup (<10 s) |
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4. Corneal Staining | Ocular surface evaluation | Fluorescein Rose bengal or lissamine green dye |
Staining observed of mucus strands, filaments, and unprotected areas of the epithelium Staining patterns can designate severity of dry eye |
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5. Schirmer 1 Test or Phenol Red Thread Test | Tear secretion rate | Schirmer tear test strip Small thread impregnated with phenol red dye A fluorophotometer is more sensitive than either of these but is usually not available in the clinical setting |
Schirmer 1: <5–7 mm of wetting after 5 min Phenol red thread test: <10 mm of wetting after 15 s |