We measured optical and biometric parameters of emmetropic eyes as a function of age. There were approximately 20 subjects each in age groups 18-29, 30-39, 40-49, 50-59, and 60-69 years with similar male and female numbers. One eye was tested for each subject, having spherical equivalent in the range -0.88 D to +0.75 D and

Of the commonly used chromatic dispersion equations, only the Sellmeier and the Cauchy equations seem to be theoretically based. Cauchy's equation is derived from the Sellmeier equation, is simpler to implement, and was found to give an excellent fit to published refractive-index data of the human eye. We used Cauchy's equation to model the chromatic difference in refraction of the Gullstrand number 1 schematic eye with a gradient-index lens. To estimate the dispersion at different refractive-index levels within the lens, a single dispersion equation at one nominal refractive index was linearly scaled. This scaling was justified after exploring the effect of mean refractive index on dispersion by using Sellmeier's equation and finding that a dispersion equation for one wavelength is just a linearly scaled version of the dispersion equation at any other wavlength. Because Cauchy's equation is theoretically based and gives excellent fit to data in the visible spectrum, it can be used to extrapolate results into the near infrared with confidence.

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There is a wide variety of optical instruments where the human eye forms an integral part of the overall system. This book provides a detailed description of the visual ergonomics of such instruments. The book begins with a section on image formation and basic optical components. The various optical instruments that can be adequately described using geometrical optics are then discussed, followed by a section on diffraction and interference, and the instruments based on these effects. There are separate sections devoted to ophthalmic instruments and aberration theory, with a final section covering visual ergonomics in depth. Containing many problems and solutions, this book will be of great use to undergraduate and graduate students of optometry, optical design, optical engineering, and visual science, and to professionals working in these and related fields.