Introduction

Anatomy

Light waves enter the eye in the following order:

• Cornea: transparent covering in front of the eye.
• Aqueous humor: viscous substance between the cornea and the lens.
• Pupil: opening within the colored part of the eye, iris
  • The pupil opens and closes to regulate the amount of entering light
• Lens: focus the light waves on the retina at the back of the eyeball
  • The lens is held in place by the suspensory ligament.
• Ciliary muscles: change the shape of the lens in order to focus the image on the retina
  • These lens changes are called accommodation.
• Vitreous humor: transparent substance between the lens and the retina
• Retina: light-sensitive inner lining of the eyeball.
  • Contains two kinds of photoreceptors: Rods (sensitive…

Functions of Eye

Dark and Light Adaptation

Dark Adaptation

• After exposure to bright light when a person goes into a dark room, the time, which it takes to see properly in dark, is called dark adaptation. In bright light cones are active, while in dark rods become active.
• The cones can adapt to darkness but still require a moderate amount of illumination. Rods can adapt to the dark with decreasing illumination. The process of dark adaptation involves changes …