Final answer:
The primary function of photoreceptor cells in the retina is to detect light and convert it into electrical signals for visual perception.
Step-by-step explanation:
The primary function of photoreceptor cells in the retina is to detect light and convert it into electrical signals that can be interpreted by the brain as visual information. The two major types of photoreceptor cells in the retina are rods and cones. Rods are more sensitive to light and enable us to see in low-light conditions, while cones are responsible for color vision and work best in bright light.