OBJECTIVES:

Preservative-free eye drops are usually single-dose vials so that it is recommended to discard the vial upon first use even if there is any remaining solution. This study aims to discuss the infection possibility of multiple uses of these eye drops and evaluate the economic impact of such action.

METHODS:

80 vials were divided into 4 equal groups, with one control group (c) and three groups. Volunteers resembled three different installation techniques to simulate using these eye drops in reality. The vials were then recapped and kept in the refrigerator for 24 hours. Next, the remaining solution in each vial was cultured as well as group C vials, and contamination and infection rates were compared between each group against the control group by using Fisher`s exact test. The infection probabilities were applied to a decision tree model to compare the cost of reusing the vials.

RESULTS:

pathogenesis rate relative to the control group for Group A was (4/20) (20%) P ≥ 0.10, while group B got only 1 out of 20 (5%) P ≥ 1.0, finally group D (5/20) (25%) P ≤ 0.04 and this was the only group that showed a significantly higher rate of pathogenicity as an indicator to the importance of the instillation technique. By applying this probability to a base case decision tree after considering possible diseases the cost saving ranged between 20.4 and 20.1 EGP (about 1.3 U$) over a 10-day period of outpatient treatment of the ophthalmic diseases.

CONCLUSIONS:

Reusing unit-does eye drops is associated with low infection possibilities using the proper instillation technique. Following this technique is associated with cost savings. Confirmation of these results are warranted studying real-actual patients with glaucoma.