Selecting the ideal HA in Dry Eye Disease: new data highlight the ideal profile of Vismed!
Hyaluronic acid is considered today as the essential component of a large variety of eye drops commercialized for the treatment of Dry Eye Disease. There is however a paucity of data evaluating the quality of HA in these products and a better characterization of these solutions is needed. Paschier and colleagues therefore worked on determining the molecular weight (MW), viscosity, pH and osmolarity of 37 products commercialized in Europe, including Vismed Multi and Vismed Gel Multi.
The following results were reported for Vismed and Vismed Gel:
|
|
HA concentration |
Molecular weight |
pH |
Mean osmolarity |
Mean viscosity |
|
Vismed |
0.18% |
1.3 MDa |
7.31 |
150 mOsm/kg |
20.75 mPa.s |
|
Vismed Gel |
0.31% |
1.3 Mda |
7.23 |
156 mOsm/kg |
50.32 mPa.s |
As expected, in comparison with other products, Vismed and Vismed Gel demonstrated a much lower osmolarity and a viscosity in the upper range. Additionally, the hyaluronic acid present in Vismed and Vismed Gel had the highest MW among all tested products. On the other hand, some other well-known eye drop products were identified with a lower hyaluronic acid MW (300 kDa).
The molecular weight can be seen as a surrogate of hyaluronic acid quality as low-MW HA (<500 kDa) was demonstrated to be pro-inflammatory in several models. On the opposite, high-MW HA (> 1MDa) has been reported to stay for a longer period on the ocular surface (longer retention time) thanks to strong interactions with the mucin layer (increased muco-adhesion). Products containing high-MW HA should therefore be favoured in order to minimize inflammation risks and to increase retention time.
Beside MW, the concentration of HA is also of importance as it directly impacts the viscosity and the shear-thinning behaviour of the final product. A higher concentration of HA has consequently been demonstrated to significantly improve tear break-up time and ocular straining. However, the optimal eye drop formulation should also not be excessively viscous, to avoid inducing blurred vision.
Key points to remember:
- Eye drops are not equivalent, and the quality of hyaluronic acid might have an impact on treatment efficacy.
- Products with high-MW hyaluronic acid (above 1 million Dalton) should be favoured to increase retention time and decrease the risk of having pro-inflammatory fragments. Vismed and Vismed Gel were reported to have the highest HA MW among tested products whereas many other products in the market had a HA MW of 500 kDa or lower.
- The shear-thinning behaviour of HA was more pronounced in Vismed and Vismed Gel than in other products, thanks to their high viscosity. The shear-thinning properties of eye drops are key to ensure that the solution spreads properly over the entire ocular surface and this study once again illustrates the good profile of TRB products.
The full study is available here: https://pubmed.ncbi.nlm.nih.gov/39225713/