I tried without glasses.That ,at this point in my life, means a very sharp front sight, blurred rear and blurred target. I shoot a M29 44mag patridge sights. Not just for target I've gotten deer with it !!
It's all the front sight ! That's why IPSC shooters are always mumbling , 'front sight, front sight !'. You can work out mathematically that the front sight is the most important is the front. Now there is a problem sometimes in hunting when the deer is in the brush. For that the way to do it is to first focus on the deer for rough line up then bring back the focus to the front sight !
Remember some of the basics - you lose ground if you hold more than 10 seconds [deer may move in shorter time than that] . Practice ! Metallic silhouette is great for that .Iron sight hangun is good for about 60 yds .If you do well on target at 100 you're ready. Most of my deer were one shot kills !