Chicago-based Opternative has launched an online refractive eye exam service that helps consumers get prescriptions for glasses or contacts. According to the company, the offering is registered with ...

If you enjoyed this article, I’d like to ask for your support. Scientific American has served as an advocate for science and industry for 180 years, and right now may be the most critical moment in ...

Please provide your email address to receive an email when new articles are posted on . It would seem logical that emmetropia is the ideal refractive state of the eye. Emmetropia puts far away objects ...

Based on: The Determination of the Refraction of the Eye with the Ophthalmoscope. By Edward G. Loring, M. D. New York: Wm. Wood & Co. 1876.