How Your Eye Works

Because most of us depend on our vision to engage with the world around us, of our five senses, sight is particularly invaluable.

The eye itself is an amazing structure, with many parts that each contribute to forming a clear image for us to enjoy. Here’s how it works:

Light from an object enters the eyes through the cornea, which acts like a clear, protective window to the eye. It is responsible for a large part of focusing light rays in the eye. The light then passes through the pupil, which is an opening in the center of the iris, or colored part of the eye. The pupil changes size to allow different amounts of light into the eye.

Directly behind the pupil is the lens. This is also a clear structure in the eye that helps to further focus light. It is controlled by muscles in the eye that change the shape of the lens to focus on objects viewed at various distances.

Light then passes through the main chamber of the eyeball which is filled with a gel-like fluid called the vitreous. It then comes to focus on the retina, a nerve layer that lines the back of the eye. Signals are then sent to the brain from the retina through the optic nerve. The brain processes these signals and allows you to see the object in front of you.

If the light rays do not come to a perfect focus on the retina, you will have a refractive error.

Common refractive errors include:

Myopia (Nearsightedness) – Light rays come to focus in front of the retina, causing vision to be blurry, more so at a distance. This is typically caused by having a cornea that is too steeply curved.

Hyperopia (Farsightedness) – Light rays come to focus behind the retina, causing vision to be blurry, often at both near and far distances. This is typically caused by having a cornea that is too flat.

Astigmatism – Light rays come to focus at multiple points on the retina, causing vision to be blurry, often at both near and far distances. This is typically caused by an irregular curvature of the cornea.

Presbyopia – Difficulty focusing on near objects that occurs due to inability of the lens to change shape with age.