Tolerability and safety of two new preservative-free tear film substitutes.

PURPOSE: The tolerability, safety, and visual comfort of two new tear film substitutes were studied in a phase I clinical study.

METHODS

Two amphipathic lipids (phosphatidylcholine, cholesterol, sphingomyelin, and gangliosides) containing solutions (I and II) of well-defined stoichiometry, free of preservatives, were studied in 20 eyes of 20 healthy volunteers (age range, 26-32 years) in a randomized, double-blind, crossover study. Randomization was achieved by treating one eye of each volunteer four times daily for 7 days with composite solution I. The contralateral eye served as a control. After a washout interval of 7 days, the same eye was treated similarly four times daily with the solution II under randomizing conditions. Slit-lamp biomicroscopy, visual acuity, visual analog scales, and side effects were monitored at the beginning of the study weekly and for 3 weeks.

RESULTS

The tear substitutes proved to have no influence on the visual acuity and were safe and well tolerated. No allergic reactions or any other side effects such as hyperemia, corneal disturbance, and foreign body deposits were observed in any volunteer.

CONCLUSION

The biophysical properties of the amphipathic lipids comprising the two preservative-free tear film substitutes were studied in monolayer experiments. They form reversibly compressible and expandable monomolecular films at the air-water interface, a prerequisite for the mimicry of the tear film produced normally by meibomian glands. The efficacy and safety of both medications will be investigated in patients with keratoconjunctivitis sicca and dry eye syndrome in future experiments.