Power measuring in ophthalmic lenses using lateral amplification

Nowadays refractive errors in the human eye affect approximately 10% of world’s population, decreasing vision acuity and life quality. However a simple common solution is the use of an adequate ophthalmic lens. Due to the importance of ophthalmic lenses, the best measurement equipment is required for testing, these days experimental and commercial apparatus are available but with the possibility of improvement. We present a method to measure spherical and cylindrical power in ophthalmic lenses. The system uses an equation obtained from lateral amplification concept and Gauss formula to make calculations. Also an experimental setup is presented for the measurement of ophthalmic lens from -20 diopters to 20 diopters in the case of spherical lenses, and from -6 diopters to 6 diopters in the case of cylindrical lenses. The setup contains a reference object, the lens to be tested and a digital camera connected to a computer with software designed in LabVIEW for the data processing. Satisfactory preliminary results were obtained according to ISO 8598.