The density of the different types of cells here produces a lot of interesting phenomenon. I don't remember if this was mentioned in class, but if you're looking at the sky at night, you'll see a lot more stars through the corner of your eye. But when you move your eye to look at the stars, they'll disappear. That's because the rods have higher density around the fovea.
@dtseng do you mean that the rods fall off at the fovea? At night the grayscale rods are primarily used so the cones at the fovea are essentially useless. In daylight though the high density of cones at the fovea enable us to do daily tasks like read :)
Here's an easy and interesting test to find where your blind spot at the optic disc is! https://visionaryeyecare.wordpress.com/2008/08/04/eye-test-find-your-blind-spot-in-each-eye/