Changes in the evaporation rate of tear film after digital expression of meibomian glands in patients with and without dry eye.

PURPOSE: To evaluate the effect of excess meibum on tear evaporation rate in patients with and without dry eye. METHODS: Eleven healthy subjects and 16 patients with dry eye were tested. The dry eye group was divided into 2 subgroups: classic keratoconjunctivitis sicca (KCS) with clear and easily expressed meibum and KCS with meibomian gland dysfunction (MGD) with turbid secretions and difficult-to-express meibum. Evaporative measurements were performed at baseline and after digital expression of meibomian glands at 12, 24, 36, and 48 minutes. Two ranges of relative humidity were used, 25% to 35% and 35% to 45%. The data were expressed as microliters per square centimeter per minute. RESULTS: An increase in the evaporation rate of the tear film was noted for all measurements at both relative humidities in the classic KCS and KCS with MGD groups compared with healthy subjects (P < 0.05). The average evaporation rates at relative humidities of 25% to 35% and 35% to 45% were 0.056 ± 0.016 and 0.040 ± 0.008 for the classic KCS group; 0.055 ± 0.026 and 0.037 ± 0.019 for the KCS with MGD group and 0.033 ± 0.012 and 0.023 ± 0.008 for the healthy group. Also, a decrease in the evaporation rate was observed in the healthy and KCS with MGD groups between baseline and the first measurement after digital expression for both relative humidities (P < 0.05). The classic KCS group did not show any changes after expression. CONCLUSIONS: Classic KCS and KCS with MGD groups showed an increase in tear evaporation rates compared with the healthy group. Aqueous tear evaporation diminished in the healthy and KCS with MGD groups after expression of meibomian glands. However, this effect was transient and negligible after the second measurement.

Pilot, prospective, randomized, double-masked, placebo-controlled clinical trial of an omega-3 supplement for dry eye.

PURPOSE: To investigate the potential effect of dietary supplementation with omega-3 fatty acid on lipid composition of meibum, aqueous tear evaporation, and tear volume in patients with dry eye. METHODS: In a pilot, prospective, randomized, double-masked study, patients with dry eye received a daily dose of fish oil, containing 450 mg of eicosapentaenoic acid, 300 mg of docosahexaenoic acid, and 1000 mg of flaxseed oil (TheraTears Nutrition; Advanced Vision Research, Woburn, MA) for 90 days. There were 2 patient visits: baseline and final. At these visits, patients completed the ocular surface disease index to score subjective symptoms, and slit-lamp examinations, breakup time, corneal staining, Schirmer type I, fluorophotometry, evaporometry, and collection of meibomian gland secretion samples for lipid composition analysis were performed. RESULTS: A total of 36 patients with dry eye completed the study. At the end of the study, 70% of the patients became asymptomatic, whereas for the placebo group, 37% [corrected] of the symptomatic patients became asymptomatic. Schirmer testing and fluorophotometry suggested that the omega-3 supplement increased tear secretion. The lipid composition of the samples collected from the omega-3 group was found to be very similar to that from the placebo group. No trends between groups were seen for other objective parameters. CONCLUSIONS: Dietary supplementation with omega-3 fatty acids in dry eye showed no significant effect in meibum lipid composition or aqueous tear evaporation rate. On the other hand, the average tear production and tear volume was increased in the omega-3 group as indicated by both Schirmer testing and fluorophotometry.