What is the optic disk
The optic nerve exits the back of the eye through a hole called the optic disk. Since no receptor cells are located in this region, it forms a blind spot in the visual image of the external world.
Option 4) an area without receptor cells where the optic nerve leaves the eye.
The blind spot is found on the retina. It is the point where the cells are not sensitive to light due to the optic nerve leaving the eye to the brain.
The optic nerve consists of the myelinated processes of ganglion cells (figure 21), which leave the retina at the optic disc (physiologic blind spot because there are no photoreceptors). The nerve leaves the orbit through the optic canal to reach the optic chiasm located just superior to the pituitary gland.