Design, Fabrication, and Evaluation of Freeform Lenses

Ohio State University, Columbus OH

Investigators

Linked publications & trials

Abstract

? DESCRIPTION (provided by applicant): Progressive addition lenses (PALs) are an important segment of the ophthalmic industry in North America and abroad. They are routinely used as spectacle lenses to correct refractive errors, and to provide a range of spherical powers to compensate for the decline in accommodation with age. In addition, there is a great need for refractive error and presbyopia correction in developing regions of the world. Design properties and optical characteristics of PALs are largely hidden from the practitioner, much less the consumer, making it difficult for either to make truly informed decisions about what lens would best address a particular set of needs. The first aim of this project is to fully develop approaches to PAL design that are flexible and transparent, which makes design decisions and optical characteristics of the resulting lenses customizable and selectable. A second aim of the project is lens fabrication. Currently, ophthalmic lens fabrication typically involves casting of lenses. Injection molding is a low-cost alternative. A component of this second aim of the project is the development of a process of injection molding to create a low cost manufacturing process. Challenges in injection molding are refractive index variation and geometric deformation of injection molded lenses. If uncompensated, these degrade the optical performance of injection molded lenses, and we will further develop a finite element modelling method to address those issues. The third aim of the project is to develop methods to measure the optical properties of progressive lenses under as-worn conditions. Precise metrology of lenses is used to refine the design of lens surface shapes, to result in a lens that conforms to the design goal. The immediate goals of the project are to develop these capabilities in lens design, fabrication, and measurement. The long term goals of the program are farther reaching: they will require extensive testing with human subject research participants. With the tools developed in this project, we will be equipped to embark on clinical testing with human subjects. The results will also potentially demonstrate the production of ophthalmic quality lenses at low cost, for use in vision correction in under-resourced parts of the world.