[Changes in the precorneal tear film at various stages of keratoconus].

The combination of keratoconus (KC) with signs of dry eye disease (DES) has been described in numerous scientific publications. At the same time, there is a relationship between KC stage and an increase in the severity of DES symptoms, however, there is still no common understanding of the severity of xerotic process depending on the clinical course of keratectasia.

Purpose: This study assesses the changes in the state of the precorneal tear film in KC relative to the stages of the disease.

Material and methods: The study included 50 patients (100 eyes) with bilateral non-operated KC from subclinical to stage IV. The following methods were used for a comprehensive assessment of the condition of the tear film: biomicroscopy of the anterior segment of the eye using vital dyes, functional tests (Norn, Schirmer, Jones tests), tearscopy of the lipid layer of the tear film with software processing of the results, OCT-meniscometry, as well as filling out the OSDI questionnaire by patients.

Results: The following significant changes were revealed as the KC stage progressed: an increase in the area of staining of the ocular surface with vital dyes, a decrease in the results of the Norn functional test and OCT-meniscometry, an increase in the areas of smaller thickness of lipids and areas of their complete absence according to tearscopy, as well as an increase in scores of the OSDI questionnaire.

Conclusion: A comprehensive assessment of the condition of the tear film in KC indicates the relationship and the strengthening of the signs of DES as keratectasia progresses, and can be considered as justification for the need to prescribe tear replacement and reparative therapy that improves the condition of the ocular surface and stabilizes the precorneal tear film.