Optical determination of internal radius of contact lenses - uses microscopic observation of crystalline structure of central point of lens

摘要

The optical device described enables the distance between the central internal point of a flexible contact lens and its base-cord support to be measured. The pointer translates this into an internal radius on a graduated drum plate. The device depends upon microscopic observation of the crystalline structure of the central internal point of the lens. The lens, in a state of hydration, is placed with its internal face pointing towards the base of a fixed immersion tank having an extractor basket with a perforated central region and a proximating reference standard covered by a magnifying lens. The control is achieved using an eye-piece (12) or an inspection screen fixed to an inverse stand, comprising a prism or a return minor.