What is the best technique to evaluate the movement of a thin hydrogel lens?

The push-up test is considered the best technique to evaluate the movement of a thin hydrogel lens. This method involves gently pushing the lens upward on the eye with a finger and observing how it responds. A properly fitting hydrogel lens should move slightly with this maneuver, indicating that it is neither too tight nor too loose.

This technique allows for a clear assessment of lens behavior on the eye, which is crucial for determining if the lens is functioning correctly and providing optimal comfort and vision. When executing the push-up test, the practitioner can observe the degree of movement and whether the lens returns to its original position, offering insights into the fit and stability of the lens on the cornea.

In assessing the suitability of the other options, none provide the direct, observable assessment of lens movement in the same way. The rotation test focuses on the lens's rotational alignment, visual assessment relies on subjective observations, and the lens displacement test also serves a different purpose by measuring how far the lens moves from its initial position. Therefore, the push-up test is most effective for directly evaluating lens movement and fit.