These are the items that I'm going to use. You can use a pen/pencil.

First, draw a slightly arched line.

Then draw another slightly arched line down, curving towards the inside.

Then draw an almost full circle inside as the iris.

Next, draw a small slanted oval in the upper left corner of the circle. It's going to represent the reflection of the light.

Next, draw almost a full big oval in the inside of the circle. Don't draw it over the small oval.

Then shade the big oval completely dark.

After that, you shade in the rest, except the small oval, from dark to light.

Then add those two lines above the eye to show the eyelid.

After that, you can add an eyebrow. You can shape the eyebrow however you want or you can copy mine.

Then you can add the eyelashes if you want.

Oh, and I almost forgot! Draw a small arched line where the arrow is pointing.

Now you can add hair and everything to go along with the eye and you're done.