There was a fellow on this forum the other day who was describing his vision situation and said he bought a Walther .22 with a laser sighting system. He claims he really enjoys it and the laser sight helps with the difficulty transitioning from close focus to distance focus.
In fact, LaserMax markets their products that way, this is from the LaserMax website:
http://www.lasermax.com/about/why.php
[snip] Compensate for diminishing eyesight
Between the ages of 40 and 50 years we start to lose the ability to change focus from distant to close objects. Many shooters give up when this happens. Don't! Just use the LaserMax laser, and focus on the target where you see best. [/snip]
It makes sense to me that a laser sight can assist people suffering from certain kinds of eyesight trouble, or at least help them compensate. Once you have it dialed in, it makes sense that you'll be looking and focusing primarily downrange to put the dot on the target there, rather than picking up the sights and then shifting downrange or vice-versa. And you're looking to superimpose a bright dot on the target.
However, with macular degeneration, you're actually losing the ability to see -- but not as a result of a focusing problem
per se. Depending on how serious it is, a laser may not help, or only help at first. Also, macular degeneration affects color perception. If the damage is so profound that he already can't see anything clearly in that area of the visual field, a laser may not be of much use.
For daytime and particularly outdoors, maybe a green laser would be better, with the caveat about green lasers not working too well in the cold (below 40 degrees F), and being more expensive because they're the "latest thing".
I think the only other thing I can say is: "Try it. Find someone with a laser sight, maybe someone with both a green and a red laser, and ask if you can borrow their pistol for some target practice."
He will know if he can or cannot see the laser, and if it is helping.