Though intracanalicular inserts occlude the punctum, they weren’t found to increase ocular allergy symptoms. Researchers suggest that increased tear conservation may dilute allergens. Photo: Alan Kabat, OD. Click image to enlarge.

Punctal occlusion is commonly used to treat dry eye by slowing tear outflow. There’s been some question as to whether this mechanism may also trap allergens on the eye’s surface for longer periods of time and increase allergy symptoms. However, a study published this month in Current Eye Research reported that punctal plugs don’t worsen ocular itching or redness.

The post-hoc analysis included three randomized, double-blind, placebo insert-controlled trials of 128 healthy patients with ocular and perennial/seasonal allergies. The researchers employed a modified version of the conjunctival allergen challenge model. This model included repeated allergen challenges at nine timepoints after placement of an intracanalicular insert.

All subjects underwent punctal occlusion with a polyethylene glycol-based hydrogel insert that contained no drug or active ingredient. The mean ocular itching score at baseline was 3.52. Mean itching scores were significantly lower on post-insertion days seven, 14 and 28 (2.62, 2.26 and 1.91; reduction: 26%, 36% and 46%, respectively). The mean baseline conjunctival redness score was 2.97. Redness scores on days seven, 14 and 28 were 1.98, 1.90 and 2.08, demonstrating significant reductions by 33%, 36% and 30%, respectively.

Based on these findings, the researchers concluded that “punctal occlusion with a resorbable hydrogel intracanalicular insert didn’t worsen ocular itching or conjunctival redness in subjects with allergic conjunctivitis.”

“Likely, allergens on the ocular surface might become diluted due to tear conservation,” the researchers surmised in their paper. “Further, the hydrogel insert doesn’t completely occlude the punctum during the first few weeks, thus allowing additional drainage compared with a true punctal plug. It’s possible that the upper punctum may acclimatize to lower punctal occlusion and, as a result, drain more.”

The study was sponsored by Ocular Therapeutix, maker of intracanalicular inserts for dry eye and ocular allergy.