Ironically, dry eye can be a rather slippery disease. Its etiology isn’t consistent in every case, and the damage dryness causes to biological structures can make them even more susceptible to further damage. A team of Finnish researchers are hoping to put a stop to this vicious cycle with a sacha inchi microemulsion (SIME) drop.1

Sacha inchi, a perennial plant native to tropical South America, produces seeds rich in omega-3 and omega-6 fatty acids that have piqued researchers’ interests in recent years. While this study used 0.1% seed oil, the entire plant has been used in clinical research to create nutritional, cosmetic and pharmaceutical products.2

Their research thus far, published in Acta Ophthalmology, shows the drop is safe and efficacious in improving each etiologic factor for dry eye disease (DED) as revealed through objective tests. The idea is that the formulation can disrupt that self-perpetuating cycle of dryness via biophysical protection of the ocular surface, facilitating the body’s ability to resolve cellular damage and inflammation, ultimately leading to a relief of symptoms.1

The research was based on the 2017 Tear Film and Ocular Surface Society’s (TFOS) Dry Eye Workshop II (DEWS II) report and its updated pathophysiology of DED. That report points to a three-part chain of causative events: (1) tear film instability, causing and accompanied by (2) localized hyperosmolarity, leading to (3) epithelial damage and inflammation. Armed with this information, the investigators speculated that it would “be possible to design a locally acting treatment modality which attenuates all etiologic factors simultaneously,” the article explains. “Targeting one etiologic segment alone might make it less likely ‘to prevent a return to the vicious circle’” of dry eye.1

The team decided to explore the potential of a multi‐ingredient SIME eye drop designed to target (1) tear film instability, (2) tear hyperosmolarity and (3) ocular surface damage and inflammation in moderate or severe dry eye. The study looked at 64 adults. It first tested one eye of each patient with SIME for one day, then treated randomized eyes with SIME and a 0.2% hyaluronic acid (HA) control eye drop three times a day for 10 days. A final part used that same randomized treatment on both eyes three times a day for 30 days.1

The investigators tested for superiority of SIME over HA using the ocular surface disease index (OSDI) and other ocular assessments. When treated with SIME and a 0.2% HA control eye drop three times a day for 10 days, mean tear break-up time (TBUT) increased by 134% in eyes with SIME and by 105% with HA by the tenth day. Blink rate decreased from 19.2±7.4 to 12.9±4.4min−1. Ocular protection index (OPI) increased in both eyes by 59% with SIME and by 41% with HA.1

In the third part of the test, TBUT increased significantly—by approximately 50%—in subjects using SIME compared with only 25% (insignificant) in the HA controls. OPI also improved significantly by 57% with SIME—it was only a 4% improvement using the HA drops.1

“The lipid component with sacha inchi is a novel supplement which improves ocular surface protection and tear film characteristics in addition to HA, trehalose and glycerol,” the study authors conclude in their paper.1 

1. Laihia J, Järvinen R, Wylęgała E, Kaarniranta K. Disease aetiology-based design of multifunctional microemulsion eye drops for moderate or severe dry eye: a randomized, quadruple-masked and active-controlled clinical trial. Acta Ophthalmol. October 3, 2019. [Epub ahead of print].

2. Wang S, Zhu F, Kakuda Y. Sacha inchi (Plukenetia volubilis L.): Nutritional composition, biological activity, and uses. Food Chem. 2018 Nov;265:316-328.