Lipid-containing eye drops: a step closer to natural tears.

Disturbances of the lipid composition can, like mucin or fluid deficiency, cause 'dry eye'. The substitution of the lipids of the tear fluid has previously been unsatisfactory since eye ointments containing fats can lead to a considerable deterioration of the visual acuity due to the film of ointment resulting from an irregular spreading behavior. We proposed the introduction of physiological lipids that are normally present in tear fluid, such as phospholipids, saturated and unsaturated fatty acids and triglycerides, to provide lipid-containing eye drops. These best correspond to 'natural tears' and, due to the small size of the lipid particles, avoid a disturbance of the spreading behavior of the lipid layer. With lipid-containing eye drops of this kind, we carried out the following examinations: inquiry of patients' symptoms based on a standardized interview; Schirmer test under local anesthesia; break-up time (BUT); biomicroscopic evaluation of the lipid film, and stability tests as pH, gas chromatographic analysis of the fatty acid pattern and thin-layer chromatographic analysis of the lipid pattern. Schirmer test, BUT measurement and questioning about symptoms were undertaken after 1 week and then again after 3 weeks of treatment. All three parameters finally showed an improvement with a high statistical significance (p less than 0.001). The stability tests have shown that pH, lipid particle size, fatty acid and lipid composition of the examined lipid-containing eye drops were nearly unchanged till 4 months after preparation.