Contact Lens Testing
Contact lenses, one of the most widely used medical devices in the world, are primarily used for eyesight correction, but also for aesthetic enhancements and modifications. They are manufactured in a variety of forms, but are most commonly made from soft polymeric materials. Because soft contact lens material is slippery and delicate to handle, loading the specimen into grips can be challenging, and tears in the lens are common even under very low forces. To best simulate how they will be used, contact lenses should be tested in physiologically relevant conditions, which requires the lenses to be tested in a saline bath, heated to body temperature.
For testing contact lenses, we recommend using a Universal Testing System configured with the BioBath, 250 N submersible pneumatic grips, and extra long surfalloy grip faces. The long grip faces enable the user to insert the small lens into the grips with enough room to maneuver, while allowing the user to achieve zero grip separation. The lenses can be tested as full final products, cut into strips, or sliced to perform a trouser tear type of test. A low force load cell is also recommended to accurately detect specimen failure. The 250 N pneumatic submersible grips and associated pull rod that attach to the load cell are both designed to minimize buoyancy chances during low force testing, such as contact lens testing.