Sterile hyaluronic acid solutions

A process for sterilizing a solution comprising hyaluronic acid, the process comprising:

• providing an aqueous solution of hyaluronic acid with a weight average molecular weight from 0.6 MDa to 2.2 MDa, and the concentration of the hyaluronic acid is from 0.08% to 0.5% by weight;
• wherein the aqueous solution has an ionic strength equivalent to an aqueous concentration of sodium chloride from 4% to 18% by weight to provide a high salt, hyaluronic acid solution;
• maintaining the aqueous high salt, hyaluronic acid solution at a temperature from 50° C. to 75° C. for at least 1 hour and not longer than 18 hours;
• and
• filtering the heated, high salt, hyaluronic acid solution through a sterilization filter medium, wherein the filter medium has an average pore size of 0.25 μm or less to provide a sterilized high salt, hyaluronic acid solution.

A process of preparing a production batch of a contact lens care solution, the process comprising:

• providing an aqueous solution of hyaluronic acid with a weight average molecular weight from 0.6 MDa to 3.6 MDa, and the concentration of the hyaluronic acid is from 0.04% to 0.8% by weight;
• wherein the aqueous solution has an ionic strength equivalent to an aqueous concentration of sodium chloride from 2% to 30% by weight to provide a high salt, hyaluronic acid solution;
• maintaining the aqueous high salt, hyaluronic acid solution at a temperature from 55° C. to 75° C. for at least 1 hour and not longer than 12 hours;
• filtering the heated, high salt, hyaluronic acid solution through a sterilization filter medium, wherein the filter medium has an average pore size of 0.25 μm or less to provide a sterilized high salt, hyaluronic acid solution;
• combining the sterilized high salt, hyaluronic acid solution with an aqueous solution comprising buffer components and adjusting the pH from 6.4 to 7.2, and by the combining of the two aqueous solutions the sterilized high salt, hyaluronic acid solution is diluted by a factor of at least 10.