Evolution Of Tear Film Osmolarity After Corneal Refractive Surgery And Comparison Between Two Tear Substitutes.

To investigate tear film osmolarity and dry eye symptoms (measured by the OSDI questionnaire) following corneal refractive surgery (PRK or LASIK) and to compare the changes in tear film osmolarity and dry eye symptoms between two different concentrations of sodium hyaluronate (SH) tear substitutes.

Citadelle Hospital, Liège, Belgium, ophthalmology department

Tear film osmolarity (TFO) and OSDI questionnaire scores (OSDI) were assessed preoperatively (day 0), on day 1, day 7, and day 30 after the corneal refractive surgery (LASIK or PRK). Patients were randomized into two groups based on the tear substitute assigned: 10 patients received a tear substitute containing 0.3% SH (group0.3; Neovis® Gel Multi, Horus Pharma - France) and 10 patients received a tear substitute containing 0.2% SH (group0.2; HyloGel®, Ursapharm - Germany).

40 eyes of 20 consecutive patients were included in the study. TFO was 307.0, 304.5, 303.5 and 304.2 mOsm/L, respectively at day 0, 1, 7, and 30, with no significant difference observed.

OSDI was 10.5, 27.4 (p=0.002) and 14.6 (p=0.6) at day 0, 7 and 30 respectively.  

Comparing group0.2 and group0.3, TFO and OSDI did not show significant differences throughout the study.

For group0.2, TFO was 305.4, 303.9 (p=0.46) and 305.3 mOsm/L (p=0.94), respectively at day 0, 7 and 30. OSDI was 5.8, 20.5 (p=0.02) and 8.4 (p=0.49), respectively at day 0, 7 and 30.

For group0.3, TFO was 307.9, 303.9 (p=0.34) and 301.7 mOsm/L (p=0.023), respectively at day 0, 7 and 30. OSDI was 15.53, 35.9 (p=0.05) and 20.2 (p=0.56), respectively at day 0,7 and 30.

Our study revealed no significant increase in osmolarity following corneal refractive surgery in patients treated with either 0.2% or 0.3% SH. One month after the surgery, TFO was significantly lower than baseline in the 0.3% SH group, while it returned to pre-operative values in the 0.2% SH group. Administration of 0.3% SH also appeared to have a better protective effect on patient symptomatology compared to 0.2% SH. These findings suggest that a higher concentration of SH and lower osmolarity could enhance objective and subjective tear quality parameters after refractive surgery. Larger studies are needed to confirm these results.