Abstract: Impression cytology and dry eye signs/symptoms

How closely does impression cytology correlate with dry eye signs and symptoms? Not very, apparently.

[Clinical- histological correlation in pacients with dry eye.]
Arch Soc Esp Oftalmol. 2010 Jul;85(7):239-245.
[Article in Spanish]
Morales-Fernández L, Pérez-Álvarez J, García-Catalán R, Benítez-Del-Castillo JM, García-Sánchez J.
Unidad de Superficie ocular, Hospital Clínico San Carlos, Madrid, España.

AIM: It is well known that there is a lack of association between symptoms and signs in patients with dry eye disease. The purpose of this study was to assess if there was any agreement between common dry eye diagnostic tests and to compare them with impression cytology.

METHODS: A total of 40 patients were enrolled in this cases-controls study. The group of cases consisted of 20 patients previously diagnosed with dry eye and the controls were 20 volunteers. The examination included: the quality of life test OSDI, break up time test (BUT), fluorescein staining, Schirmer's test and finally the study of goblet and conjunctival epithelial cells with impression cytology. The Student t and U Mann-Whitney tests were used to evaluate the results, and Spearmańs Rho coefficient to assess their correlation.

RESULTS: Statistical differences were observed between cases and controls Group for all tests (P<0.0001). After assessing the good correlation between BUT, fluorescein staining and Schirmer's test, we studied their association with the impression cytology. The number of isolated goblet cells showed a weak association with the majority of tests, however the grade of metaplasia showed a greater association.

CONCLUSION: Impression cytology is a valuable test in the diagnosis of dry eye. Although the number of goblet cells is not a sufficient diagnostic criterion, its joint assessment with the grade of metaplasia and the other dry eye tests is useful.