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This abstract is assigned to session AOB Free Papers

Presentation type	Oral presentation
Title	Evaluation of tear film osmolarity changes after corneal refractive surgery and comparison between two tear substitutes

Purpose	To evaluate tear osmolarity and dry eye disease (DED) symptoms (OSDI questionnaire) changes after corneal refractive surgery and compare evolution of these parameters between 2 different concentrations of sodium hyaluronate (SH)tear sustitute(TS)
Methods	Tear osmolarity and OSDI were measured before and 1,7 and 30 days after a surgery.Patients were divided in 2 groups according to the prescribed TS.10 patients received 0.3% SHTS(NeovisGel Multi,HorusPharma) and 10 patients received 0.2% SHTS(HyloGel,Ursapharm)
Results	We included 40 eyes from 20 consecutive patients.In the overall population,we observed no significant difference between preoperative and any postoperative values of osmolarity (307.0, 304.5, 303.5, 304.2mOsm/L at day0, 1, 7 and 30,respectivelly).OSDI worsened at day 7(10.5 to 27.4;p=0.002) with no difference at day 30.When comparing 0.2% SH and 0.3% SH groups,tear osmolarity and OSDI were not significantly different at any time.However, evolution was different between groups when compared to baseline.Osmolarity dropped at day 1 in 0.2% SH group and went back to preoperative values at day 30.In 0.3% SH group,osmolarity decreased at day 7 and reached significance at day 30(301.72;p=0.02). Regarding OSDI,0.2% SH group showed a significant worsening after 7 days with no difference after 30 days.In 0.3% SH group, OSDI showed no significant variation
Conclusion	Our study showed no significant increase in osmolarity after refractive surgery.After 30days, osmolarity was significantly lower than baseline in 0.3% SH group with no difference in 0.2% SH group.The results of this study indicate that higher concentration of SH and lower osmolarity could improve parameters of DED post refractive surgery.Larger studies are needed to confirm our findings
Conflict of interest	No

Authors 1

Last name	CRAHAY
Initials	F
Department	Citadelle
City	Liège

Authors 2

Last name	Papart
Initials	S
Department	Citadelle
City	Liège