Guest Editorial: Defocus and daily life.

For example, while many studies have examined defocus and clinical visual acuity,1 fewer could be found on the effects of defocus on common activities such as maintaining posture,2,3 walking,4-6 driving7-9 or playing sports.10-12 With regard to driving, it was interesting to read Wood I et al i .'s study13 in the current issue specifically addressing whether 0.5 D of defocus could affect pedestrian detection in night driving. Of these, spherical and astigmatic defocus are common due to refractive errors, and presbyopia and accommodative anomalies can lead to spherical blur. Detailed field studies of real tasks - as found in these two examples, and others - can be combined with knowledge of the other contributors to understand how defocus may be important in specific daily activities. Sources of blur in the eye include spherical and astigmatic defocus, chromatic and monochromatic aberrations, scatter and diffraction. [Extracted from the article]