Association between Dry Eye Parameters Depends on Tear Components.
How tear components contribute to dry-eye symptoms/signs remains less well-defined. This observational cross-sectional study enrolled 4817 (F/M = 3590/1227) patients. Subjective symptoms were evaluated with the SPEED and OSDI questionnaires. Fluorescein tear breakup time (FTBUT), superficial punctate keratitis (SPK) grading, Schirmer scores, number of expressible meibomian glands (MGE), lipid layer thickness (LLT), blink/partial blink rates and meibography were recorded. Patients were divided into 4 types according to their Schirmer scores and LLT, i.e., Type 1 (N = 1494): Schirmer > 5 mm, LLT > 60 nm; Type 2 (N = 698): Schirmer > 5 mm, LLT ≤ 60 nm; Type 3 (N = 1160): Schirmer ≤ 5 mm, LLT ≤ 60 nm; Type 4 (N = 1465): Schirmer ≤ 5 mm, LLT > 60 nm. Lipid deficiency (LLT ≤ 60 nm) and aqueous deficiency (Schirmer score ≤ 5 mm) were found in 38.6% and 54.5% of patients, respectively. The majority (62.4%) of lipid-deficient patients were also aqueous deficient, while 44.2% of aqueous-deficient patients were also lipid-deficient. Type 3 patients (mixed type) had the highest symptom scores (p = 0.008 and 0.007 for SPEED and OSDI, respectively), more total blinks (p
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