We see structure of an eye on the picture below.
The root has to have thick eyelashes and thin on tips.
As you should not draw eyelashes see below.
Draw with light lines an eye contour. Then 2H draw with a pencil eyelashes. Each eyelash looks, as the comma only turned. Draw from an eye contour thus reduce pressing a pencil bending the line, the line will become is thinner. The easy movement of a brush tear off a pencil from paper when stop drawing an eyelash.
2B draw with a pencil still eyelashes that they were dense. draw a contour of an iris of the eye, a pupil and a patch of light.
6B draw with a pencil a pupil. 2B draw with a pencil an eye iris of the eye. For this purpose we use gradient shading by ringlets. Pay attention that from above eye area more dark, than below, on each side too it is darkened. An eraser will walk for creation of light area from below, then put some lines for creation of texture.
Using cross shading create gradient transitions on a white of the eye, thus edges and up a squirrel have to be darkened. Make shading of edges of the upper and lower eyelid, transition of tone is closer to an external corner of an eye to become is more dark. Draw a few thin lines to create blood vessels.