Question

Should a sensible retina have more foveas (or larger ones, perhaps) or might peripheral retina be more than leftover real estate?

Answer 1

Answer:

Eye is a sensory organ of vision, which enables us to see the objects. In humans, two eyes are situated in the orbital cavity of the skull, the eye balls of the eye are supported by a number of accessory structures.

Eye ball is a three layered structure, the outer layer is cornea, the middle layer includes, choroid, ciliary body and iris, the inner nervous coat contains, retina.

Rods and cones: These are functional components of the eye. It is illustrated that sensible retina have more foveas or larger ones because cones are predominantly located densely in the center of the retina of eye and this area is referred as “fovea” here it is profoundly found that there are no presence of rods because the area outside the fovea centralis is peripheral retina and it has more rods. These rods are more sensitive to incident light compared to sensitivity of cones.

Mechanism of ight involves the following steps:

1. Light enters the eye through the cornea
2. Iris and pupil regulate the amount of light entering the eye
3. The image is then focussed through the lens on the retina
4. The pigmented choroid darkens the interior of the eye. This reduces scattering and reflection of light.
5. The image then stimulates the receptors present in the rods and cones of retina (neural layer).
6. These impulses are then carried through optic nerve.
7. The optic nerves of both sides cross at optic chiasma.
8. From the optic chiasma, the impulses are carried by optic tract to visual cortex present in the occipital lobe of brain, where the image is perceived.
9. The primary visual cortex of cerebral area VI and 17. This is surrounded by calcarine sulcus and it is also called as striate cortex associated with granular layers predominantly composed of dense columns of neurons. These neurons are called as ocular dominance columns. Adjacent columns and regions are connected from the same homonomous portions of the both left and right optic connections.