Twenty-six patients (mean age, 58.8 years) with dry-eye syndrome (aqueous-deficient keratoconjunctivitis sicca) were randomly assigned to receive a placebo or a combination of linoleic acid (57 mg/day) and gamma-linolenic acid (30 mg/day) orally for 45 days. All patients used substitute tears four times a day. Compared with placebo, active treatment resulted in a significant improvement in symptom score (p < 0.005), staining with lissamine green (p < 0.005) (an objective measure of dryness of the eyes), and ocular surface inflammation (p < 0.05).

Comment: There is evidence that chronic dry eye disease is caused in part by inflammation of the lacrimal glands and the ocular surface. Gamma-linolenic acid (GLA) has anti-inflammatory effects, and has been found previously in a small clinical trial to relieve dryness of the eyes in people with Sjogren’s syndrome or dryness caused by certain medications. The amount of GLA used in the present study was small – approximately 10-30% of the amount used in previous studies. A typical 500-mg capsule of evening primrose oil contains 45 mg of GLA. It is unlikely that the linoleic acid used in this study was responsible for the improvement, since the average diet contains considerably more linoleic acid than the 57 mg/day given as a supplement.

Barabino S, et al. Systemic linoleic and gamma-linolenic acid therapy in dry eye syndrome with an inflammatory component. Cornea 2003;22:97-101.