The human eye consists of three layers - an outer protective layer, a middle layer that regulates the pupil and light entrance, and an inner retinal layer containing photoreceptors. The retina contains both rod and cone photoreceptors. Rods provide peripheral and low-light vision while cones provide sharp central vision and allow for color perception. The overlapping visual fields of the two eyes allow for stereoscopic 3D vision.

1. THE SENSE OF VISION-EYE
LIFE SCIENCES: GRADE 12

2. T
• The human eye consist of photoreceptors known as photoreceptors that are
sensitive to light.
• Both animals and humans have 3D or stereoscopic vision, this means that their eyes.
• Each eye is able to view objects from different angles because visual fields overlap.

3. THE HUMAN EYE CONSIST OF THE
FOLLOWING PARTS
1.Outer layer of the eye
-The sclera( which is the white outer layer that has two important functions,
protecting and supporting the eyeball.)
-Transparent membrane that moisten the eye surface.
- The cornea( the transparent part of the eye that refracts light rays.
**The sclera, conjunctiva and cornea make up the outer layer of the eye.

4. 2.MIDDLE LAYER OF THE EYE
• -Pupil (The black hole in the eye that admits light into the eye.
• -Iris (is the coloured part of the eye that has two important functions viz, regulates
the size of the pupil and light entrance).
• Lens ( is the transparent biconvex structure of the eye that refracts and ensures that
light focuses on the retina.

5. 3.INNER LAYER
• Consist of the retina- which is made up of photoreceptors called cones and rods.
• Rods-provide overview sight (make black and white vision possible)
• Cones- provides colour vision.
• Blind spot- area where nerves and blood vessels enter and leave the eye. Provides
no vision.
• Fovea centralis-offers best image possible.

6. *CONES
• The cones are located in the fovea centralis, cones become less away from the fovea centralis.
• They are activated by bright light and allow us to detect fine detail and colour.
• Cones have three pigments namely Blue, Green and Red.
• Lack of certain cones causes color blindness.

7. *RODS
.Contain a deep visual pigment call rhodopsin.
They are sensitive to light and suited for night vision and peripheral vision.
. They are found on either side of the fovea and the further
Away from the fovea.

9. THE EYE CONSIST OF TWO CAVITIES
• A. The anterior cavity:
-consists of watery aqueous humor which is produced by the ciliary body.
B. Posterior cavity:
-Is filled with jelly like vitreous humor.

10. • Reference list
• Designua (2019) “Shutterstock images”. Available from
https://www.shutterstock.com/image-vector/schematic-structure-rod-cell-
peripheral-vision-117137794. Accessed on 8-11-2019.