**3.5 Mucoadhesive delivery using polymers**

Hydrophilic polymers must be employed to construct the liquid ophthalmic delivery mechanism since they may serve as a useful viscosity altering or boosting agent. In the ophthalmic mucoadhesive delivery method, polysaccharides are often employed. Hyaluronic acid, methylcellulose, hydroxypropyl methylcellulose, chitosan, gellan gum, carrageenan, xanthan gum, and guar gum are some of its variants. Chitosan is a polysaccharide polymer made up of polysaccharides. It is appropriate for usage in medication compositions due to its biodegradability, low toxicity, and biocompatibility [83]. Polyvinylpyrrolidone, poloxamer, and polyvinyl alcohol are among additional non-ionic polymers utilized for mucoadhesive characteristics [84].
