How the human eye works: a guide to understanding your vision

Published on 18 March 2025 · Updated on 18 March 2025

The human eye is one of the body's most fascinating and complex organs. Its main function is to capture light, transform it into electrical signals and send them to the brain to be interpreted as images. In this article, we explain step by step how the eye works and why caring for it is so important.

The process of vision, step by step

1. Light enters the eye

Light enters the eye through the cornea, which acts as a transparent window that focuses light rays. It then passes through the pupil, whose opening is regulated by the iris (the coloured part of the eye) to control the amount of light entering.

2. Focusing the image

Light passes through the crystalline lens, a flexible lens that adjusts its curvature to focus on objects at different distances. When we look at something close up, it becomes more convex, and when we look into the distance, it flattens to focus the image correctly on the retina.

3. Capture by the retina

The retina is a thin layer of tissue at the back of the eye containing millions of light-sensitive cells called cones and rods.

• Cones allow colour perception and work best in good light.
• Rods are more sensitive to dim light and help with night vision.

4. Transmitting information to the brain

Information captured by the retina is converted into electrical signals that travel along the optic nerve to the brain. This is where the magic of vision really happens: the brain interprets the signals received and turns them into clear, understandable images.

The importance of caring for eye health

The human eye works in synchrony with the brain to let us see the world around us. To maintain good eye health, regular ophthalmic check-ups, protecting the eyes from ultraviolet light with sunglasses and a diet rich in antioxidants are essential.

Caring for our eyes is key to healthy vision and a better quality of life. If you notice changes in your vision or eye discomfort, consult an ophthalmology specialist.

Did you find this article interesting? At Clínica Castellote we specialise in eye care. Contact us for a check-up and keep your vision in the best possible condition. Please follow us on Facebook and Instagram to learn much more about your vision. You can also read our latest articles on the blog, where we discuss different eye conditions, symptoms and treatments.