Assessing visual function in clinical practice

Abstract

Examination of the afferent visual system involves a structural assessment of the eye, the associated neurological structures, and the ocular adnexa, in addition to an evaluation of afferent visual function. The most common measure of visual function is Snellen visual acuity, which provides a rapid and useful measure of some aspects of central visual function but is a subjective parameter that conveys limited information regarding the overall function of the visual system. A wide variety of psychophysical and electrophysiological tests have been developed to capture various aspects of visual function more thoroughly. The main goal of this issue of the Ophthalmology Clinics of North America is to provide a comprehensive overview of tests that are currently available to practicing clinicians and promising new technologies that may eventually provide useful clinical information. This issue begins with a summary of techniques for evaluating the afferent pupillary light response. This often-underemphasized aspect of the afferent visual examination provides the only objective information regarding visual function that is readily available to a clinician during a routine eye exam. The articles by Kniestedt and Stamper, Swanson and Cohen, and Anderson review the evaluation of visual acuity, color vision, and standard perimetry, which, along with pupillary assessment, form the backbone of the clinical evaluation of visual function in standard practice. Owsley reviews contrast sensitivity, which is not used as often as it should be in clinical practice but nevertheless provides a more comprehensive measure of central function. Specialized tests of peripheral function are summarized by Anderson and Johnson and Racette and Sample for both short-wavelength automated perimetry and frequency doubling technology perimetry, which are designed to emphasize specific ganglion cell subpopulations and improve the sensitivity of visual field testing. Finally, Holopigian and Hood provide a thorough overview of the broad topic of electrophysiology; this article reviews tests that are useful in elucidating causes of occult visual loss (eg, electroretinography, electro-oculography, and visual-evoked potentials) as well as more recent developments in this area, including multifocal electrophysiologic techniques. Robbins and colleagues and Schneck and Haegerstrom-Portnoy tackle the difficult problems associated with visual function assessment in pediatric and elderly populations. These articles provide readers with practical tips and guidelines for the examination of these more challenging patients. Finally, Ball brings the assessment of visual function out of the clinic and laboratory in her summary of visual function in the real world. This