Have you though on what happens if want to image the eye fundus of a person with astigmatism. The answer is that as the person sees but due to the his astigmatism, we will see bad his eye fundus. So correction of the astigmatism is important for seeing and for watching inside the eye.
I show you here two videos in order to provide you the experience of watching the difference between observing the retina without correcting the astigmatism of the subject or after correction.
In this first video , we see the the retina without astigmatism correction. The vessels are more blured in the vertical direction than in the horizontal, that is due to the astigmatism and its orientation.
In the next video I show you the same retinal area but with astigmatism correction.
You can see more defined vessels, even you can see the lood flow as a light spark in small capillars.
THAT IS AMAZING.