Cameron,
I am now in my 50s and I have to wear bifocals or progressive lenses.  For me, I can see the target better with a scope.  At the distance small game is normally taken, a scope is not needed.
When I was in the Army, it was obvious that as it gets dark the iron sights get close to invisible.  A scope will make the target easier to see, as the light fades.  However, the cross-hairs also start to disappear as it gets dark.  Glowing cross-hairs and  a white or tritium front sight could be a wonderful thing.
Only hits count.  
Accuracy comes from a good barrel, trigger and sights.  Focus on the front sight/cross-hairs and concentrate on the trigger.  <img src="/images/graemlins/cool.gif" alt="" />   
_________________________
Thermo-regulate, hydrate and communicate.