Trabeculectomy Reduces Tear Level of Pro-Inflammatory Lipid Mediators

Trabeculectomy significantly decreased the level of some proinflammatory lipid mediators at 3 years postoperatively, while increasing the level in those who needed postoperative bleb needling at 1 year, according to a study published in The Ocular Surface. This is possibly due to an inflammatory process associated with fibrosis, the investigators reported.¹

The researchers conducted the longitudinal interventional cohort study at the Singapore National Eye Center following prior research that revealed the relevance of tear lipid mediators (also called oxylipins) in ocular surface disease.^1,2 These mediators are involved in both acute inflammation and inflammation resolution.¹

Because of the potential link between trabeculectomy and ocular surface disease, the study authors sought to examine tear lipid mediator changes, post-trabeculectomy, in this new study. They prospectively evaluated 33 patients undergoing trabeculectomy, collecting tear fluid using Schirmer’s strips, both preoperatively and postoperatively. They analyzed lipid mediators with liquid chromatography mass spectrometry.¹

Patient follow-up was devised at 4 time points: baseline, 6 months, 1 year, and 3 years. Not all 33 patients made it to the study’s end point, however: At 3 years, 11 patients had completed follow up; at 1 year, 22 patients had; and at 6 months, 27.¹

Results showed that normalized concentrations of 40 lipid mediators were between 0.1 and 8.0 ng/mL. Docosahexaenoic acid (DHA), Arachidonic acid (AA), and eicosapentaenoic acid (EPA) ranged up to a few hundred ng/mL. Concentrations of lipid mediators, except DHA, EPA, and thromboxane (TXB1), were decreased after surgery. At 3 years follow-up, lipids 8-HETE, 15-HETE, 15-oxoETE, 11-HDoHE, 17-HDoHE, and 20-OH-LTB4 were significantly reduced.¹ 

Increases did occur, however. From baseline to 6 months, researchers found that an increase in the level of lipid mediator 2,3-dinor-8-isoPGF2α was associated with inferior corneal staining.¹

“The association of the inflammatory lipid mediators and corneal staining may reflect inflammatory ocular surface epithelial damage, since F2-isoprostanes (iPF2α), non-enzymatic products of arachidonic acid peroxidation, are inducers of oxidative stress,” according to the study.¹

A significant increase was also seen in 6 lipid mediators at 1 year in the 14 patients who required postoperative bleb needling compared with those who did not. In those cases, patients might have had a chronic underlying inflammatory process connected to fibrosis.¹

The study suggests that patients with a higher level of 2,3-dinor-8-isoPGF2α before surgery might require targeted postoperative corneal epithelial status management. Additionally, those who required needling to maintain surgical success might need more bleb monitoring at 3 months postoperative “in view of the suspected ongoing fibrotic process.”¹

The study did have limitations: Authors didn’t perform standard force expression to evaluate meibomian glands status, and some patients were lost to follow-up.¹

References

1. Ambaw YA, Wong T, Chong R, et al. Change of tear lipid mediators in a post-trabeculectomy cohort. The Cornea Surface. 2020:18(4):565-574. doi: 10.1016/j.jtos.2020.06.004.

2. Ambaw YA, Chao C, Ji S, et al. Tear eicosanoids in healthy people and ocular surface disease. Scientific Reports. 2018:8:11296. doi: 10.1038/s41598-018-29568-3.