Levels of lactoferrin, lysozyme and albumin in the tear film of keratoconus patients and their correlations with important parameters of the disease

Abstract Background : Despite the fact that keratoconus has been tipically defined as a noninflammatory condition, recent research has promoted the role of inflammatory factors and protein changes of tear film in disease progression. Aims : to determine the level of serum albumin, lactoferrin and lyzozyme in tears of keratoconic patients and their correlations with corneal biomechanical properties. Subjects and methods: 16 eyes of keratoconus patients and 14 eyes of control cases were enrolled in an observational prospective study. We performed a complete ophthalmological examination on all participants. In order to determine the concentration of tear film proteins, a minimum of 20 microlitres of tears from the lower conjunctival fornix were collected from each subject and measured by enzyme-linked immunosorbent assay (ELISA) analysis. Results: The level of lactoferrin measured in the tear film was significantly decreased in the keratoconus group compared to the normal subjects in all cases (p<0.05). We also found an increased level of lyzozyme and albumin in the keratoconus patients when compared to the controls, only the lyzozyme beeing statistically significant. In the keratoconus group, the correlations between proteins and important parameters such as keratometry, pachymetry and corneal biomechanics were statistically relevant in our study. Conclusions : We can state that the protein composition of tears is modified in keratoconus by increased levels of protein with inflammatory properties such as albumin or by decreased levels of protein with anti-inflammatory properties such as lactoferrin.