Structural changes in the cornea and tear film in keratoconus associated with dry eye syndrome on the background of the use of optical correction and tear replacement therapy

Introduction . The literature data confirm a relationship between keratoconus (KC) and signs of dry eye syndrome (DES). The scleral rigid gas permeable contact lenses widely used in the optical correction of keratoconus are more often used in the treatment of dry eye syndrome to protect the cornea and tear film. Aim . To evaluate changes in the condition of the cornea and tear film in keratoconus associated with dry eye syndrome during the use of scleral rigid gas permeable contact lenses in combination with/without tear replacement therapy. Materials and methods . A total of 30 patients (60 eyes) with bilateral stabilized non-operated keratoconus at different stages associated with dry eye syndrome were examined. The patients were divided into groups: Group 1 included 15 patients (30 eyes), who used 0.9% sodium chloride (saline solution) as a moisturizing solution to fill the lens cup before it was placed in the eye; Group 2 included 15 patients (30 eyes) who used 0.18% sodium hyaluronate as a moisturizing solution. All patients underwent the following examinations: biomicroscopy of the anterior segment of the eye using a vital dye (0.1% fluorescein sodium) and assessment of the degrees of epitheliopathy of the conjunctiva and cornea according to the Oxford grading system, determination of the precorneal tear film break-up time (Norn test), as well as the status of total (Schirmer test) and basic (Jones test) tear production. Results and discussion . Wearing scleral rigid gas-permeable contact lenses, regardless of the type of solution filled into the lens cup before placing it in the eye, improves significantly the ocular surface condition and increases the results of function tests. Conclusion . The observed tendency towards a higher capacity to repair corneal tissues during the use of 0.18% sodium hyaluronate preservative-free tear replacement agent in the sublens space is confirmed by corneal confocal microscopy outcomes and indicates the greater efficacy of using a combination with a tear replacement agent.