title: Dynamic strain gage measurements on ophthalmic lenses impacted by low energy missiles.
abstract: Strain distributions on impacted ophthalmic lenses were measured with strain gages. The strain distributions, which resulted from impacts produced with a special apparatus, were shown to be comparable to those which arise in the FDA drop-ball test. The measured strain drops off very rapidly away from the impact point, implying that only a small part of the lens is really being tested. The results are in good agreement with the quasi-static predictions. The effect of differences in lens power, of input kinetic energy, and of inserting the lens in a polyethylene bag are also investigated.
mesh_terms: D005069:Evaluation Studies as Topic; D005139:Eyeglasses; D006245:Hardness Tests / Q000295:instrumentation / Q000379:methods; D008433:Mathematics; D011312:Pressure; D014481:United States; D014486:United States Food and Drug Administration