I'd like to share with my web design team some specific, quantitative data on just how much visual ability changes, even as young as 40 years old. This is to help drive home the need for adequate font size & contrast. I've found references about this, but they are not as convincing as I'd like. I'd really like references from either peer reviewed journals or well-known organizations. Here's what I've found so far:
Visual Forensics of Older Drivers by Marc Green -http://www.visualexpert.com/Resources/olderdrivers.html Has some good quantitative info on changes with age, "at age 60, the amount of light reaching the photoreceptors is only 33% of the amount seen at age 20. By the late seventies, the amount falls to 12%. Further aging reduces light transmission even more as the effect accelerates." But I'm afraid someone on my team might wonder if this guy is really is an expert.
Fonts, Typography, And How We Read Online by Susan Weinschenk - http://www.blog.theteamw.com/2011/06/03/first-podcast-kevin-larson-2/ "when you are 40 years old only 1/2 of the light in your environment makes it through to your eye." - there's no specific reference other than the podcast & the info isn't mentioned in the link to another article that's included in the blog.
Age Related Functional Limitations: Vision by W3.org - www.w3.org/TR/wai-age-literature/#whatvision - Interesting specifics on , but several of the source links are broken.