Study of Tear Film and Ocular Surface in Keratoconus

ABSTRACT

PURPOSE: To evaluate the changes of tear film and ocular surface in keratoconus patients. METHODS: Twenty-eight eyes of 18 patients with keratoconus and 32 eyes of 16 normal subjects were included. We performed corneal sensitivity test, tear film break-up time (BUT), Schirmer test, fluorescein and rose bengal staining, and conjunctival impression cytology, and compared the results between the two groups. According to the central corneal power, we classified the patients into 3 groups and compared these parameters between groups. RESULTS: Corneal sensitivity was 5.56 +/- 0.34 mm and 5.88 +/- 0.25 mm (p<0.001), BUT was 9.64 +/- 2.51 sec and 10.69 +/- 2.89 sec (p=0.008), basal tear secretion was 9.00 +/- 3.06 mm and 10.88 +/- 3.95 mm (p=0.025), fluorescein staining score was 1.43 +/- 1.87 and 0.69 +/- 1.20 (p=0.105), and rose bengal staining score was 0.86 +/- 0.97 and 0.22 +/- 0.55 (p=0.003) in the patients and control subjects, respectively. The degree of conjunctival squamous metaplasia was 1.04 +/- 0.51 and 0.62 +/- 0.43 (p=0.039), and goblet cell density was 762.65 +/- 76.32 cells/mm2 and 880.21 +/- 82.06 cells/mm2 (p=0.041) in the patients and control subjects respectively. All parameters except basal tear secretion and fluorescein staining score were related to the severity of keratoconus. CONCLUSIONS: Tear film and ocular surface changes in patients with keratoconus are composed of decreased corneal sensitivity, decreased quantity and quality of tear film, and damages to corneal and conjunctival epitheliums, which are similar to the findings in keratoconjunctivitis sicca.