From Ian Gilbert
Cambridge University’s John Daugman believes that human iris patterns change
negligibly over time
(11 August, p 16). The plastic eye I now use, made 20 years
ago when I was 38 years old, is still a perfect match for my biological eye. But
the previous prosthetic eye had to be replaced after 13 years because the iris
of my remaining eye had changed after I was 25. And the plastic eye that I got
when I was 16 lasted only nine years before it got out of synch with my
biological iris.
It may be that iris scans of teenagers, or even of under-thirties, may have
to be retaken at regular intervals. If my experience is typical, the makers of
artificial eyes may have some useful information for Daugman.
Washington DC
