what nerve allows you to focus your eye
The fovea is an important region of the retina, as it contains the highest concentration of photoreceptors in the eye. Nervous tissue in the retina is connected to the brain through the optic nerve, which passes through a hole in the choroid and sclera in the posterior of the eye. Where the optic nerve forms there are no photoreceptors, resulting in a blind spot known as the optic disk.
Light projects through the pupil and the lens to the back of the eye. The inside lining of the eye is covered by special light-sensing cells that are collectively called the retina. The retina converts light into electrical impulses. Behind the eye, the optic nerve carries these impulses to the brain. The macula is a small extra-sensitive area within the retina that gives central vision. It is located in the center of the retina and contains the fovea, a small depression or pit at the center of the macula that gives the clearest vision.