This shows how important it is to always be more focused on the main target or the main problem too.... The eye is a very critical part of the body and can influence other areas, including what you'll do. The brain can only interpret what the eyes sees. If you're not seeing it clearly then your brain will interpret it blurry as you've seen it.
What an insightful post
Also explains how players suddenly lose form as it is to do with the concentration levels and being focused.