Optical Projection System Design for Both Distant and Near Eye Charts.

In this study, a digital eye chart optical projection system for distant and near vision examination was designed using the basic principle of geometric optics and a Snellen chart, which consists of four modules: an off-axis parabolic (OAP) mirror, a triplet lens, an liquidcrystal display (LCD), and a digital processing unit. Fifteen male subjects participated in the experiment, and their visual acuity data were recorded. The system shows the benefits of compactness, portability, and easy operation, in comparison with the traditional design. A detailed design process has been addressed in this paper. [ABSTRACT FROM AUTHOR]