Question

In mammalian eyes, the fovea is the center of the visual field where
A. More rods than cones are found
B. High density of cones occur but has no rods
C. The optic nerves leaves the eye
D. Only rods are present

Answer 1

In the centralis area there is a small depression, namely the fovea centralis, which is the area with the sharpest colour vision. Images of objects we see directly (i.e. those in the middle of our field of vision) fall on this very sensitive part of the retina .

Complete answer:
The human eye is a very delicate and delicate organ that enters the orbit and protects it from injury. It mainly consists of cornea, lens and retina.
Cornea: This is a translucent membrane that covers the visible part of the eye. The black part (such as brown, blue, or other shadow) is the iris, which is visible through the cornea. The perforated and perforated iris is called the pupil.
Lens: The lens is visible through the pupil. It is a colourless biconvex crystal lens that divides the eyeball into two spaces, one filled with a fluid known as the aqueous humour and the other having the vitreous humour. The lens creates a true image of the inverted retina.
Retina: This is the sensitive part where the image of the object we see is formed.
The rods and cones are unevenly distributed on the retina. The shape of the cone is pyramidal while the stem is cylindrical. However, the shape of the cone varies in different parts of the retina.
The small area of ​​the retina that is parallel to the optical axis is called the yellow dot or centralis area, which contains many cones.
Optic nerve: These nerves send sensations to the brain and help us visualize objects.
The optic nerves leave the eye and retinal blood vessels enter it at a point medial to the posterior pole of the eyeball. The point on the retina, at which optic nerves leave the eyeball, is called the blind spot Photoreceptor cells rods and cones are not present in the blind spot. No image is formed at this point that’s why it's called blind spot.
At the posterior part of the ball of eye lateral, a yellow pigmented spot is present known as macula lutea. It is also called a yellow spot. There is a central pit present on the macula lutea which is called fovea centralis.
The fovea is the thinned out portion of the retina where only the cones are densely packed.

Hence from the above points it’s clear that the correct option is (B).

Note: The yellow spot, blind spot and fovea are present on the retina.
Fovea is the point where resolution or visual acuity is greatest and vision is sharpest.
Outside the fovea, on the retina, often serve photoreceptor cells (present on the outer portion of the retina)and several bipolar cells synapse with a single ganglion cell (present in the inner portion of the retina). This results in convergence of information.
The fovea is responsible for acute central vision (also known as foveal vision), which is required in humans for activities where visual details are critical, such as Reading and driving. About half of the nerve fibers in the optic nerve contain information from the fovea, while the other half contains information from the rest of the retina.