Abstract: AIMTo evaluate how solution viscosity affects the precorneal residence of five water-soluble polymers with different properties. METHODSCaptive bubble technique was used, with the consecutive change of contact angle interpreted as an indication of desorption process, to study the residence of those polymers in vitro on freshly enucleated rabbit eyes under physiological conditions. RESULTSCarbopol and sodium hyaluronate (HA), which adsorbed to isolated ocular surface more than 15 min, showed the optimum precorneal retentive capabilities. When the solution viscosity increased from 12 mPa·s to 50 mPa·s, the residence time of carbopol and HA were prolonged 10 min and 7 min, respectively, but that of sodium carboxymethylcellulose was not affected. CONCLUSIONThe result suggested that higher viscosity is beneficial to improve the ocular residence time of bio-adhesive polymers.