Many shooters see an irregular shape of a fuzzy dot when using red dot optics. Chances are, the image is perfectly round and you have a mild astigmatism. Not to get all sciencey on you, astigmatism simply means your eye isn’t perfectly round. Almost everyone has it to some degree and it affects what you see and how you shoot.
A normal eyeball is shaped like a sphere. When light enters, it bends evenly, allowing you to focus. If you have an astigmatism, your eye is irregularly shaped like a football. The light gets bent and only part of an object is in focus. Objects or red dots, may look blurry or irregular.
Trainers don’t usually talk about astigmatism unless they have one. Some shooters have gone through a series of optics or just said “I can’t use red dots”.
Another way to check this is to take a picture of the red dot in your sight. If the red dot is bad you will see it in the picture. If it’s good, there will be a round dot and the problem is in your eyes.
TWANGnBANG has done a great video that gives you an easy test for astigmatism and more importantly, some solutions to the fuzzy red dot.
Photo courtesy of tipdisease.com