Question

Give an account of the retina of the human eye.

Answer 1

• The retina is the innermost tunic of the eyeball. It is a thin, delicate and transparent membrane. It appears purplish red in colour.
  
• The retina is composed of three distinct regions. They are Optic disc, macula lutea and peripheral retina.
• It's composed of several layers, including one that contains specialized cells called photoreceptors.
• There are two types of photoreceptor cells in the human eye : rods and cones. Rods are located throughout the retina; cones are concentrated in a small central area of the retina called the macula.
• At the center of the macula is a small depression called the fovea. The fovea contains only cone photoreceptors and is the point in the retina responsible for maximum visual acuity and color vision.
• Rod photoreceptors detect motion, provide black-and-white vision and function well in low light.
• Cones are responsible for central vision and color vision and perform best in medium and bright light.
• Light rays are focused by the cornea and lens onto the retina, where vision begins. Photoreceptor cells take light focused by the cornea and lens and convert it into chemical and nervous signals which are transported to visual centers in the brain by way of the optic nerve.