Question

Give the difference between Blindspot and Yellow spot.

Answer 1

Hint: The blind spot of the right eye is present slightly to the right of the centre of vision and that of the left eye is present slightly to the left of the centre of vision. When both eyes are open, the blind spots are practically not perceived as the visual fields of both the eyes overlap.

Complete Step by Step answer:
At the beginning of the optic nerve in the retina of the eye, there is a spot free from rods and cones. This spot is devoid of the ability for vision and is called the blind spot. On the other hand, the yellow spot (macula) lies a little lateral to the blind spot.

Blindspot	Yellow spot
- Blindspot is a spot on the retina present at the point of origin of the optic nerve.	- Yellow spot is the small area on the retina present at the posterior pole of the attention, lateral to the blind spot.
- Photoreceptor cells are absent from this region.	- Photoreceptor cells are absent from this region.
- They are insensitive to light as they don't have both rods and cones are absent.	- They are insensitive to light as both rods and cones are not present in them.

Additional Information: In the blind spot, there are no photoreceptors, i.e., neither rods nor cones, and, therefore, there is no image formation in this area. This is because of the lack of both rods and cones which means no detection of both light or colours.
Rodes
- Rodes are distributed over most of the retina except near the fovea.
- No rods at all in the central part of the fovea.
- Rods are connected in groups, there are far fewer optic nerves going to the brains than rods.
- Rod vision detects edges and motion very well.
- Rod pigments are bleached by light and are less effective in bright light, rods take about 20 to 30 minutes of dark adaptation before they are most efficient.
Cones
- There is a concentration in the fovea, a region about 1.5 mm in diameter. Most acute visions are limited to foveola, covering nearly 0.4 mm.
- Color vision is provided by three types of cones with different coloured light absorption red, green and blue cones.

Note:
- Although all vertebrates have the blind spot in the retina, cephalopods which have only superficially similar eyes, lack this area. In these organisms, the optic nerve approaches the receptors from behind which results in no break in the retina.