TP=/Re: PD causes in personal history. I heard that Edward Weston & Margaret Bourke-White, both pro photographers had PD, as do I. I've been an amateur photog for about 50 years(which is hard when you're only 39 ;) ) and worked for a commercial photo-finisher for about 3 handling & hands-in typical B&W photo chemicals. Anyone see a common thread? Thanks. Don Voegeli [log in to unmask] $&ik