Figure 7.

Suggested mechanisms of HMWHA eye drops in the treatment of dry eye disease. HMWHA eye drops have two main functions. One is the retention of aqueous and secretory mucin in the aqueous layer. This effect reduces friction between the eyelids and the ocular surface and, consequently, reduces the ocular surface damage and inflammation. The tear film stability is enhanced by the reduction of ocular surface damage and the retention of aqueous and secretory mucin in the aqueous layer. The second function is the anti-inflammatory effect, which can maintain secretory mucin Muc5AC expression. This action also increases the stability of the tear film. The parts surrounded by red boundaries are those mechanisms proved by the current research, and the other parts are speculative mechanisms which need to be clarified in future studies. HMWHA, high molecular weight hyaluronic acid (HA).