how thick is the cornea and is a protective skin layer for pupil and Iris?

Question

how thick is the cornea and is it a protective skin layer so if you get a scratch where the center of the eyeball is will it protect the pupil and iris?

Answer 1

Here you go:
"the cornea has a diameter of about 11.5 mm and a thickness of 0.5 mm - 0.6 mm in the center and 0.6 mm - 0.8 mm at the periphery" (See source link).

The cornea does provide protection, and it also refracts (bends) light so you can focus on what you are looking at.

The eyelids and eyelashes provide the most protection for the eye (along with the blink reflex).