Purpose: To observe and classify tear film lipid layer interference patterns in normal volunteers and dry eye patients and to investigate the relation between the lipid layer interference patterns in the dry eyes and the results of other dry eye examinations.
Methods: Precorneal tear lipid layer interference patterns were observed at the central cornea in 25 eyes of 13 normal controls and 85 eyes of 48 dry eye patients. Observed patterns were classified in masked fashion by five physicians into five grades: grade 1, somewhat gray color, uniform distribution; grade 2, somewhat gray color, nonuniform distribution; grade 3, a few colors, nonuniform distribution; grade 4, many colors, nonuniform distribution; and grade 5, corneal surface partially exposed. Other methods of dry eye examination were also performed, including the cotton thread test, the Schirmer I test and modified Schirmer I test, measurement of tear film breakup time, scoring of corneal fluorescein staining density (grades 0 to 3) and area (grades 0 to 3), and rose bengal staining (grades 0 to 9).
Results: In 92 (84%) of 110 eyes, four or more of the five physicians agreed in their grade classifications. Among the 92 eyes, normal control eyes were classified into grades 1 and 2 (10 and 12 eyes, respectively) and dry eyes were classified into grades 2, 3, 4, and 5 (22, 26, 10, and 12 eyes, respectively). There was a significant correlation between the grading and the results of other dry eye examination modalities, including fluorescein staining, rose bengal staining, and tear film breakup time.
Conclusions: Tear lipid layer interference patterns are highly correlated with dry eye severity.