Visual Physiology: Photoreceptor Cells - Rods and Cones

Our eyes are remarkable organs that rely on specialized photoreceptor cells—rods and cones—to process light and enable vision. These cells are located in the retina and play crucial roles in detecting light intensity and color.

Structure and Function of Photoreceptor Cells

Rods

Rods are highly sensitive to low light levels and are responsible for night vision. They contain rhodopsin, a light-sensitive pigment that enables vision in dim environments.

Cones

Cones function in bright light and allow for color vision. There are three types of cones, each sensitive to different wavelengths: red, green, and blue.

Role in Visual Processing

Light entering the eye stimulates rods and cones, triggering electrical signals that are transmitted to the brain via the optic nerve. These signals are processed by the visual cortex, allowing us to perceive images and colors.

Common Disorders Affecting Photoreceptors

• Retinitis Pigmentosa: A genetic disorder causing progressive rod cell degeneration, leading to night blindness.
• Color Blindness: A condition resulting from defective cone cells, affecting color perception.
• Macular Degeneration: A disease primarily affecting cone cells, impairing central vision.