To establish the effect of lipid supplements on tear lipid biochemistry and their influence on lens wear comfort in habitual lens wearers.Methods
Forty habitual soft contact lens wearers were recruited to a double-masked, randomized crossover trial. An emulsion drop containing phosphatidylglycerol (Systane Balance; Alcon) and a liposomal spray containing phosphatidylcholine (Tears again; BioRevive) along with saline placebos were used three times a day for 14 days with 48 hours of washout between each intervention. The Contact Lens Dry Eye Questionnaire categorized participants into symptomatic and asymptomatic wearers. Ocular comfort was measured using the Ocular Comfort Index. Basal tears (15 μl from each eye) were collected with lenses in situ and assayed for the concentration and activity of phospholipase (sPLA2) and the concentration of a malondialdehyde (MDA). Electrospray ionization mass spectrometry characterized the tear lipidome.Results
Neither of the lipid supplements improved lens wear comfort compared to baseline. The spray treatment did not affect the concentration of the majority of lipid classes either at day 1 or at day 14. Both the lipid and placebo drops resulted in increased concentration of several lipid classes after day 1 of use, but by day 14, the concentration of most of the lipid classes had returned to baseline levels. With the lipid spray, sPLA2 activity (0.38 ± 0.2 vs. 0.73 ± 0.6 mmol/min/ml, p = 0.03) and lysophosphatidylethanolamine (LPE) (1.3 ± 0.5 vs. 2.7 ± 0.07 pmol/μl, p = 0.02) were higher in the symptomatic group compared to asymptomatic group at day 1 but not at day 14. The lipid drop resulted in increased LPE concentration in symptomatic wearers at day 1 (1.7 ± 0.3 vs. 2.4 ± 0.3 pmol/μl, p = 0.01) and at day 14 (1.7 ± 0.4 vs. 2.5 ± 0.5 pmol/μl, p = 0.04). Ocular comfort was inversely proportional to the level (r = -0.21, p = 0.007) and activity of sPLA2 (r = -0.20, p = 0.01). There was an association between sPLA2 and LPC (r = 0.41, p < 0.001) and LPE (r = 0.40, p = 0.001), and a negative association with (O-acyl)-ω-hydroxy fatty acids (OAHFAs) (r = -0.30, p = 0.03) in tears.Conclusions
Contact lens wear comfort was associated with sPLA2 concentration and activity in tears. Lipid biochemistry was transiently influenced by exogenous supplements. Although the specific supplement formulations tested did not differ from placebo in this study, the results do suggest a potential role for lysophospholipids and OAHFAs in modulating symptoms during contact lens wear.