The quantity of preservative in the conjunctival sac depends on the Tear Clearance Rate (TCR) in each individual

Purpose. Preservatives in ophthalmic solutions can be a source of ocular surface problems, especially in dry eye patients. The purpose of this study is to determine whether remaining preservatives in conjunctival sac really depend on TCR. Methods. Ten microliter of artificial eye drops including 5mg/100ml benzalkonimu chloride (BC) were instilled into both eyes of 44 patients (informed consent received) (61.9+/-12.9 y.o.). Five minutes later, the ordinary Schirmer test was performed and the BC was recovered from Schirmer test strip and measured by HPLC. TCR was evaluated in each patient and compared to the quantity of BC. Results. The largest quantity of the remaining BC was 193.73ng in patients with TCR of X1 and the lowest was 34.85ng in patients with TCR of X16. There was good correlation between the remaining BC and TCR (r=.54, P=0.0002), however there was no correlation between BC and Schirmer test with or without anesthesia. Conclusions. TCR can be a better indicator for the evaluation of TCR compared to simple Schirmer test. Furthermore, this study demonstrated that the preservatives in ophthalmic solution can remain in larger quantities in the conjunctival sac of patients with low TCR.