Tear film abnormality test Dry eye test, production, secretion, staining, stability, meibomian, oil gland test

 

Dry eye disease results from either reduced tear production or instability of the tear film. Accurate diagnosis requires a combination of quantitative and qualitative tests to assess tear volume, tear film stability, lipid layer quality, and ocular surface integrity.
This post summarizes the 9 major clinical diagnostic tools used in dry eye evaluation.

🔹 Key Diagnostic Categories

1. Slit-lamp Microscopy
    - Evaluates tear meniscus height and debris in aqueous layer
2. Tear Film Stability Tests
    - T-BUT (≤10s is abnormal)
    - NI-TBUT (non-invasive method using reflected grid distortion)
    - OPI = T-BUT / IBI → Instability if <1
3. Tear Production Tests
    - Schirmer I/II (measures basal + reflex tearing)
    - Phenol red thread: less irritating alternative with color change
4. Tear Composition Tests
    - Ferning Pattern: mucus crystallization visualized
    - Osmolarity: >316 mOsm/L indicates hyperosmolarity
5. Meibomian Gland Evaluation
    - Lipid secretion analysis → evaporative dry eye assessment
6. Tear Clearance Tests
    - Measures tear drainage and residence time
    - Tear Clearance, Fluorescein Clearance, TFI
7. Ocular Surface Staining
    - Fluorescein: stains epithelial defects (mostly cornea)
    - Rose Bengal: highlights unprotected epithelial cells
    - Lissamine Green: gentle alternative for conjunctival staining
8. Functional Visual Testing
    - TSAS, FVA assess real-world visual performance over time

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📋 Dry Eye Diagnostic Summary Table (English)

Test CategoryDiagnostic GoalKey Tools / Interpretation

Slit-lamp Observation	Evaluate tear volume and debris	Tear meniscus
Tear Stability	Measure tear film breakup	T-BUT, NI-TBUT, OPI
Tear Production	Assess aqueous secretion levels	Schirmer test, Phenol red thread
Tear Biochemistry	Analyze mucin pattern and osmolarity	Ferning test, Osmolarity test
Meibomian Gland	Check meibum quality and expressibility	Meibomian gland exam
Tear Clearance	Measure tear flow and clearance time	Fluorescein clearance, TFI
Surface Staining	Detect epithelial cell damage	Fluorescein, Rose Bengal, Lissamine Green
Vision Testing	Evaluate dynamic visual performance	TSAS, Functional Visual Acuity (FVA)

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