Viscosity in an artificial tear

A viscous artificial tear stays
longer in the eye

Several studies have shown that the more viscous an artificial tear is the longer it stays in the eye. And it has been clinically confirmed that the relief a high-viscosity tear brings to the symptoms of dry eye lasts longer.

It is also true that the more viscous a humectant, the more likely it is that the user will note discomfort and blurred vision.

A difficult balance between viscosity and comfort

A formula with a viscous texture is therefore very effective for relieving dry eye, but since it can be uncomfortable for the user, it is usually recommended only for night-time use, while the user sleeps.

Producers of artificial tears face the challenge of designing a product that offers all the advantages of a viscous, gel-type tear but that is comfortable, can be used night and day and is also appropriate for contact lens users.

Dual polymer: more viscous during rest and fluid with blinking

The answer lies in the combination of components that give viscosity but without causing blurred vision. An excellent option is to use a dual polymer in the formula, with hyaluronic acid and hydroxyethylcellulose. This results in a product that is more viscous during rest and is transformed into a fluid liquid with blinking.

To explain how hyaluronic acid and hydroxyethylcellulose work, we need to first introduce some very simple concepts of chemistry.

Fluids can be classified for their viscosity as:

  • ● Newtonian fluids: viscosity is constant and does not change if a force (movement) is applied. A good example is water.
  • ● Non-Newtonian fluids: viscosity changes if a force is applied or if there is a change in temperature. Examples are glue or blood..

Hyaluronic acid and hydroxyethylcellulose are non-Newtonian fluids which are very viscous at rest (with the eye open) and become very liquid with movement (blinking).

Proof of how this dual polymer works can be seen in this video of Acuaiss Dual Gel.

Acuaiss Dual Gel hydrates the eye surface for longer, without causing
blurred vision

These two humectants have allowed for a single product: Acuaiss Dual Gel, which provides hydration for a long time and is very comfortable to use because it does not cause blurred vision.

It can be used at night and during the day and can even be applied while wearing contact lenses.

It is available in a pocket-size format of 10 ml and in single-dose packs without preservatives.