What if, instead of introducing new agents into the body, doctors could jumpstart the immune system’s natural responses? That’s the question behind much of the research into autologous serum drops, which are custom developed from an individual patient’s own biology. When the cornea’s integrity is threatened by oxidative stress, the corneal epithelium and tear fluid naturally release antioxidative enzymes to protect it. Now, researchers have pinpointed the specific serum components that exert antioxidative effects on the corneal epithelial cells in an effort to apply them to medications.

Selenium, as it turns out, is the crucial element in regulating oxidative stress in the cornea, as well as other tissue. For that reason, they point to selenium compounds as good candidates corneal treatment. The Japanese research, published in the latest issue of Cornea, found that found that selenoprotein P, a known selenium-transfer plasma glycoprotein, secretes into the tear fluid to supply the corneal epithelium with selenium. They’re hoping to parlay this finding into a selenium compound that can treat corneal disorders caused by various diseases, such as keratoconjunctivitis sicca, superficial punctate keratopathy and dry eye disease.

One compound in particular showed promise, the study says. That compound—known as Se-COMP—was used in various formulations in rodent studies for two weeks, before and after exposure to an irritant (in this case, tobacco smoke). The 0.5% and 1% formulations significantly suppressed corneal damage. The efficacy for selenium supply was then estimated by comparing the Se-COMP eye drops with those containing COMP, which has a similar structural formula to Se-COMP but lacks selenium. The 1% COMP eye drops were partially effective, whereas the 1% Se-COMP eye drops were more effective. Se-COMP is small, with a molecular weight of 2,000Da that contains one selenium atom.

Se-COMP was developed from a larger compound, Se-lactoferrin, which was also determined to be a good candidate for treating corneal disorders, but its synthesis is more expensive than existing drugs.