Human EyeHuman Eye

Human Eye

The human eye is similar to that of your camera, it gathers light, focuses the light through a lens to create an image of the environment on to the back of the camera and eye. In a camera, image is inversely created on film, whereas for the eye, the image is created on the retina at the back of the eye. The lens of a camera is used to focus the image onto the film, but the eye lens bends, or refracts, light that enters the eye.

The cornea, which is a clear, transparent covering the front portion of the eye also contributes to focusing light on the retina. Nerve fibers extending back from the retina’s nerve cells come together behind the retina to form the optic nerve, a “cable” of nerve fibers connecting the eye with the brain.

The optic nerve transmits messages about what we see from the eye to the brain. Like a camera, the human eye controls the amount of light that enters the eye through the lens under various lighting conditions.

The Human Eye which is not sphere in shape as what we think, is joined by two pieces called the cornea and the sclera. The cornea and sclera are connected by a ring called the limbus. The eye is made up of three enclosing transparent structures. The outermost layer is composed of the cornea and sclera. The middle layer consists of the choroid,ciliary body, and iris. The innermost is the retina, which gets its circulation from the vessels of the choroid as well as the retinal vessels.

human eye

The iris – the colour of the eye – and its black centre, the pupil, are seen instead of the cornea due to the cornea’s transparency. To see inside the eye, an ophthalmoscope is needed, since light is not reflected out. The fundus (area opposite the pupil) shows the characteristic pale optic disk (papilla), where vessels entering the eye pass across and optic nerve fibers depart the globe.

The Human Eye makes vision similar to that of your camera. Light enters from the cornea to the iris to the retina and with rod cells and cone cells in the retina, it allows conscious light perception and vision including color differentiation and the perception of depth.

 

  1. posterior compartment
  2. ora serrata
  3. ciliary muscle
  4. ciliary zonules
  5. canal of Schlemm
  6. pupil
  7. anterior chamber
  8. cornea
  9. iris
  10. lens cortex
  11. lens nucleus
  12. ciliary process
  13. conjunctiva
  14. inferior oblique muscule
  15. inferior rectus muscule
  16. medial rectus muscle
  17. retinal arteries and veins
  18. optic disc
  19. dura mater
  20. central retinal artery
  21. central retinal vein
  22. optical nerve
  23. vorticose vein
  24. bulbar sheath
  25. macula
  26. fovea
  27. sclera
  28. choroid
  29. superior rectus muscule
  30. retina