  Hypothesis:
  Although wetting agents have been developed to limit tear film dewetting over
contact lenses, systematic analyses correlating wetting agents properties to
mechanisms of the tear film destabilization are not readily available.
Clarifying destabilization characteristics across key physio-chemical variables
will provide a rational basis for identifying optimal wetting agents.
  Experiments:
  We employ an in-house, in vitro platform to comprehensively evaluate drainage
and dewetting dynamics of five wetting agents across seventeen different
formulations and two model tear film solutions: phosphate-buffered saline (PBS)
and artificial tear solution (ATS). We consider the film thickness evolution,
film thickness at breakup, dewetted front propagation, and develop correlations
to contact angle to compare the samples.
  Findings:
  Zwitterionic wetting agents effectively stabilize the tear film by reducing
the film thickness at the onset of dewetting, and delaying dewetted region
propagation across the lens. Furthermore, tuning wetting agent surface
concentrations in binary mixtures can enhance wetting characteristics. Finally,
despite disparities in wetting agent molecular properties, the time to dewet
$50\%$ of the lens scales linearly with the product of the receding contact
angle and contact angle hysteresis. Hence, we fundamentally establish the
importance of minimizing both the absolute contact angle values and contact
angle hysteresis for effective wetting performance.
